Prospects for the Industrialization of Nitride-Based Photocatalytic CO₂ Reduction Research Achievements: A Net Present Value Analysis

Abstract

With the annual increase in carbon emissions and the warming of the global temperature, it is imperative to accelerate the construction of a green, low-carbon, circular economic system. The photocatalytic reduction of CO₂ can convert the emitted CO₂ into valuable carbonaceous products, which is of great significance for alleviating the global CO₂ emission problem. In this study, the literature on the “photocatalytic reduction of CO₂” from two Chinese and foreign databases was used as the analysis sample. From the perspective of net present value, nitride-based catalysts were selected as the research object. An in-depth analysis of the costs and economic benefits of the nitride-based photocatalytic reduction of CO₂ was carried out, considering four factors: catalyst efficiency, light conditions, discount rate, and depreciation period. The analysis results show that with a project duration of 10 years and a discount rate of 10%, the net present values of all the catalysts are negative, indicating that from an economic perspective, investment projects using general catalysts to reduce CO₂ are not feasible under current conditions. However, it is worth noting that when the light conditions are changed and sunlight is used as the light source, the net present values corresponding to the Ta₃N₅/Bi and NiOx/Ta₃N₅ catalysts have turned positive, showing a certain economic feasibility. When the yield is increased to 2.64 times and 6.15 times of the original values, the net present values corresponding to the T-CN/ZIS (refers to ZnIn₂S₄ (ZIS) nanosheets grown in situ on tubular g-C₃N₄ microtubes (T-CNs)) catalyst and the Ta₃N₅ cuboid catalyst turn positive, and only the net present value of the g-C₃N₄/Bi₂O₂[BO₂(OH)] catalyst remains negative.

1. Introduction

Extreme weather events such as torrential rain, floods, persistent droughts, and sweltering heatwaves that are caused by global warming are wreaking havoc on marine and terrestrial ecosystems and endangering human survival and health. Greenhouse gases emitted by human activities are one of the main factors contributing to climate change and the frequent occurrence of extreme weather events. As the main component of greenhouse gases, a reduction in CO₂ emissions is urgent. In order to practice low-carbon development, China announced in September 2020 that it would strive to achieve “carbon peak” before 2030 and “carbon neutrality” before 2060 [1]. Against the backdrop of these “dual carbon” goals, the controlled conversion of carbon dioxide into high value-added chemicals or fuels (such as CH₄, CO, HCHO, etc.) through chemical methods is an effective way to achieve artificial carbon fixation and reduce carbon emissions. It is also a win–win strategy for solving energy and environmental problems [2]. Currently, the applied chemical carbon reduction technologies include four categories: photochemical, biochemical, thermochemical, and electrochemical. Among them, photocatalytic carbon dioxide reduction technology is particularly worthy of remark. It can directly convert carbon dioxide and water into hydrocarbon solar fuels relying solely on solar energy, which is both green and sustainable.

The activity of the photocatalytic reduction of CO₂ depends to a large extent on the photocatalyst. Currently, researchers have developed various catalysts for the photocatalytic reduction of CO₂ reaction, including metallic elemental semiconductors such as Ru, Ir, Pt, Cu, Pd, and Rh [3]; metal sulfide semiconductors such as SnS₂, MoS₂, WSe₂, Cu₂S, and CdS [4,5]; and metal oxide semiconductors (ZnO, Fe₂O₃, WO₃, TiO₂, and CeO₂, etc.) [6,7,8,9,10,11]. Although they have a certain catalytic activity, these catalysts usually have disadvantages such as a poor stability, high cost, the rarity of the materials, and significant harmfulness. In contrast, g-C₃N₄ and Ta₃N₅ in nitrides can have their stability and catalytic efficiency enhanced through means such as doping, compounding, and structural regulation. They are catalysts with economic prospects.

So far, most of the papers have focused on research and development, the design of the photocatalytic reduction of CO₂ catalysts, and the study of reaction mechanisms. Only a few pieces of literature have reported on the economic feasibility of photoelectrocatalysis. For example, Park et al. described the economic feasibility of electrochemical CO₂ reduction from the perspective of individual processes such as reaction and separation [12]. Huang Zhe et al. studied the economic feasibility of renewable electricity-driven electrochemical CO₂ reduction [13]. However, there is a lack of literature on the economic feasibility of the photocatalytic reduction of CO₂, especially the use of net present value to measure the economic feasibility of photocatalytic CO₂ reduction, which is rarely reported.

Exploring the economic benefits of the photocatalytic reduction of CO₂ is of great significance. From the perspective of industrial development, with the deepening of basic research, a large-scale preparation process is gradually maturing, which will attract a large amount of capital to enter the game and give birth to upstream and downstream industrial chains centered around the photocatalytic reduction of CO₂. These chains cover links such as material synthesis, equipment manufacturing, and product refining, creating a huge number of job opportunities and revenue growth points. Moreover, in fields with high emission reduction pressure such as agriculture and chemical industry, the mature application of this technology can help enterprises reduce carbon emission costs, avoid environmental protection fines, reshape the profit structure in long-term operations, reshape the green competitiveness of the industry, and continuously empower sustainable economic growth.

This study adopts a three-stage research framework of “bibliometric analysis–technology screening–economic evaluation”. Firstly, the development trend of the technology is grasped through a bibliometric analysis. Subsequently, typical catalysts are screened to establish a technical evaluation system. Finally, a financial model is established to verify their economic feasibility. The technical route covers the literature research method, comparative analysis method, and cost–benefit analysis method. Through the analysis in this paper, the current situation of this technology in the industrialization process can be revealed, enriching relevant research.

2. Research Overview of Photocatalytic Reduction of CO₂

2.1. General Trend of the Number of Published Papers

The number of published papers and their changing trends can, to a large extent, reflect the development level of a discipline and the degree of attention paid by the academic community to a certain research field. In order to comprehensively, objectively, and systematically understand and master the research progress of the photocatalytic reduction of CO₂ at home and abroad, this paper uses the China National Knowledge Infrastructure (CNKI) database and the Science Citation Index (SCI) database as the retrieval databases. The retrieval term in the former is set as “photocatalytic reduction of CO₂” and in the latter as “photocatalytic CO₂ reduction”. Through retrieval, 1104 domestic studies (CNKI) and 10,455 international studies (SCI) were obtained. A total of 11,559 relevant domestic and international studies were collected in this paper (Figure 1). Judging from the total number of published papers, the trends in the number of published papers both domestically and internationally have seen rapid growth in the past decade or so, indicating that the attention to relevant research has been continuously increasing. Domestically, the period from 1991 to 2009 was a stage of slow growth, and the growth rate significantly accelerated from 2010 to 2023. Internationally, 2008 was a watershed. Since 2008, the annual increase in the number of published papers has been relatively large.

These changes are closely related to the macro environment. On the one hand, due to the large-scale exploitation and utilization of traditional fossil energy (coal, oil, natural gas), energy consumption has soared with economic development and population growth. Activities of major carbon emission sources such as industrial production processes, the expansion of transportation, and power and heat supply have intensified, leading to a continuous increase in emissions. For example, from the second half of the 20th century to the beginning of the 21st century, the global total carbon emissions surged from several billion tons per year to over 30 billion tons. In recent years, due to the emission reduction efforts of some countries and the advancement of energy transformation, the growth rate has moderated, and there has even been a slight decline in some years. However, the overall stock remains high. Currently, the concentration of CO₂ in the global atmosphere has exceeded 410 ppm, which is approximately 45% higher than that before the Industrial Revolution [14]. To solve the difficult problem of carbon dioxide emission reduction, scientific researchers have continuously innovated and conducted research, resulting in numerous achievements.

On the other hand, the energy conservation and emission reduction policies and strategies introduced by governments around the world have strongly driven the research process in the field of CO₂ reduction technology. In March 2009, the “Report on China’s Sustainable Development Strategy 2009” issued by the Chinese Academy of Sciences put forward the goal of a low-carbon economy, aiming to reduce CO₂ emissions per unit of GDP by about 50% by 2020 [15]. In 2007, the British Parliament signed the Climate Change Act. In 2009, the United States House of Representatives passed the Cap and Trade Bill for Greenhouse Gases and the Clean Energy and Security Act [16]. In 2008, Germany launched the “Product Carbon Footprint” project. In 2008, Japan issued the Declaration of the Low-Carbon Revolution titled “A Low-Carbon Society and Japan”. These policies have promoted the research process of CO₂ reduction. With a capital injection and project support guided by policies, universities and research institutions have gathered a large number of scientific research talents, giving rise to a great many scientific research achievements. As a result, the number of relevant academic papers published in this field has been continuously rising, forming a cycle of accelerated knowledge spillover and technological iteration, providing an indispensable key driving force for CO₂ reduction technology to move from theoretical concepts to industrial practice and achieve substantial breakthroughs and development.

2.2. Analysis of the Number of Published Papers on Photocatalytic Reduction of CO₂ Under Different Catalyst Categories

In recent years, there has been a significant amount of research on vanadate-based, sulfide-based, and nitride-based photocatalysts for carbon dioxide reduction. These three series of catalysts each have their own characteristics. Vanadate-based catalysts (such as BiVO₄, CeVO₄, etc.) have a band structure that is adaptable to visible light, a variety of catalytic active sites, and they can efficiently activate carbon dioxide. However, some of them have the drawback of the easy recombination of photogenerated carriers. Sulfide-based catalysts (such as CdS, MoS₂, etc.) have a strong absorption of visible light and a narrow band gap, which is conducive to electron transition to initiate the reaction. However, they face problems such as a poor stability and potential pollution due to the presence of heavy metals. Nitride-based catalysts (typically g-C₃N₄) have inexpensive raw materials, chemical stability, and can respond to visible light. However, the migration rate of photogenerated carriers needs to be improved. The three types of catalysts have significant differences in terms of photocatalytic efficiency, stability, and environmental friendliness.

Through the statistics of the number of relevant scientific research achievements, Figure 2 clearly shows a significant trend: In the past five years, nitride-based photocatalysts have attracted the attention of the scientific research community, becoming a research hotspot and attracting extensive attention and in-depth exploration from the academic community. The total amount of research on nitride-based photocatalysts accounts for the highest proportion among the three types of catalysts: vanadate-based, sulfide-based, and nitride-based. There are many reasons behind this. The nitride-based photocatalyst family has a rich variety of members. Taking graphitic carbon nitride (g-C₃N₄) as an example, it has obvious advantages. First of all, its raw materials have a wide range of sources, the preparation process is relatively simple, and the cost is controllable, giving it a significant advantage in terms of economic cost. Secondly, it has considerable chemical stability, which can effectively cope with complex reaction environments and ensure the stability of the catalytic process. Thirdly, it can respond well to visible light and can make full use of solar energy to drive the photocatalytic reduction of carbon dioxide. With so many advantages combined, it stands out, becoming the focus of scientific research, attracting many teams to conduct in-depth research, improve its catalytic efficiency, and continuously expand the boundaries and potential of its application in the field of the photocatalytic reduction of CO₂.

3. Cost–Benefit Analysis of Nitride-Based Photocatalytic Reduction of CO₂

3.1. Selection of Catalysts

Based on the previous analysis, two series of catalysts, g-C₃N₄ and Ta₃N₅, which receive abundant research among nitrides, were selected as the research objects for cost–benefit studies. In order to further improve the photocatalytic reduction ability, researchers generally achieve this goal through various means, such as changing the catalyst structure and preparing composite catalysts. By studying relevant domestic and international literature, data related to the two catalysts, g-C₃N₄ and Ta₃N₅, were collected and sorted. Three composite catalysts with the top three yields were selected from each. The relevant data are shown in

Table 1. Catalyst products and their yields. Unit: μmol·g⁻¹·h⁻¹.

	CO	CH4	C2H5OH	References
TCN(NH3)	103.6			[17]
T-CN/ZIS	1453		863	[18]
CNBB-3	6.09			[19]
Ta3N5/Bi		4.52		[20]
Ta3N5 cuboid		0.652		[21]
NiOx/Ta3N5		32.3		[22]

. The first three are g-C₃N₄ series catalysts, namely metal-free porous nitrogen-rich g-C3N4 nanotubes (abbreviated as TCN(NH₃)), T-CN/ZIS, and g-C₃N₄/Bi₂O₂[BO₂(OH)] (abbreviated as CNBB-3); the latter three are Ta₃N₅ series catalysts, namely Ta₃N₅/Bi, Ta₃N₅ cuboid, and NiOx/Ta₃N₅.

It can be found from Table 1 that the T-CN/ZIS catalyst has the highest yield, followed by TCN(NH₃), and the NiOx/Ta₃N₅ catalyst has a relatively good catalytic performance. When studying whether a certain catalyst can be put into industrial production, the yield is an important indicator. However, it is one-sided to evaluate the performance of a catalyst merely based on the yield. Cost–benefit is also a factor that cannot be ignored, as it is directly related to the economic feasibility and market competitiveness of the catalyst in actual production and application. If a catalyst has a high yield but a high preparation cost and high usage cost, it may be difficult to promote in large-scale industrial production. Therefore, to comprehensively and objectively evaluate the performance of a catalyst, it is necessary to comprehensively consider various factors such as yield and cost–benefit.

3.2. Cost and Economic Benefit Analysis

3.2.1. Analysis of Relevant Costs

When analyzing the catalytic effect of a catalyst, we need to comprehensively consider its cost–benefit from multiple perspectives. This includes the cost of the catalyst itself, equipment investment costs, working capital advances, wage payments, and equipment maintenance costs.

Suppose an experiment on the photocatalytic reduction of carbon dioxide is conducted in Hefei, Anhui Province. Before conducting the analysis, first assume that the equipment mainly consists of several reaction kettles and a set of detection equipment. The total volume of the reaction kettles is 150 m³. After consultation, the estimated total equipment investment is 20 million yuan. Assume that the working capital advance is 10% of the sum of the equipment cost and the catalyst cost. The catalyst cost is calculated based on the dosage given in the references of Table 1. The photocatalytic reduction of CO₂ is mainly carried out under a 300 W xenon lamp simulating sunlight. The service life of a xenon lamp is approximately 800 h per unit, and the unit price of a xenon lamp is 230 yuan per unit. The number of xenon lamps placed in each reaction kettle is determined according to its effective illumination range. Combining that with the service life, the annual consumption quantity is calculated. The non-time-of-use industrial electricity charge in Anhui Province is basically around 0.7 yuan per kilowatt-hour. Calculate the annual electricity cost at 0.7 yuan per kilowatt-hour. The relevant costs are shown in the following table.

It can be observed from Table 1 and

Table 2. Analysis table of relevant costs for photocatalytic reduction of CO₂. Unit: ten thousand yuan.

	Catalyst Cost	Equipment Investment	Working Capital Advances	Annual Xenon Lamp Cost	Annual Electricity Cost	Other Annual Expenses
TCN(NH3)	0.01	2000	200.00	7590	598.75	14
T-CN/ZIS	310.95	2000	2542.05	7590	598.75	14
CNBB-3	7.88	2000	2208.66	7590	598.75	14
Ta3N5/Bi	26.90	2000	2229.59	7590	598.75	14
Ta3N5 cuboid	19.88	2000	2221.86	7590	598.75	14
NiOx/Ta3N5	20.03	2000	2222.03	7590	598.75	14

that among the composite catalysts of g-C₃N₄, TCN(NH₃) has a relatively low cost and a high yield, demonstrating good economic benefits and catalytic performance. T-CN/ZIS has a high cost but also the highest yield, showing an excellent catalytic performance. In terms of catalyst cost and yield, CNBB-3 performs averagely compared with the other two catalysts. Among the composite catalysts of Ta₃N₅, NiOx/Ta₃N₅ shows a relatively good performance.

3.2.2. Economic Benefit Analysis

Net present value (NPV) can effectively measure the economic benefits of a project. NPV refers to the difference between the present value of the expected recoverable cash in the future of the project and the investment cost of the project, which is a basic indicator of the net present value method in project evaluation [23]. Both future cash inflows and cash outflows are converted into present values according to the present value factors of each period at the expected discount rate, and then the NPV is determined. This expected discount rate is determined based on the minimum investment rate of return for the enterprise, representing the minimum acceptable threshold for investment in the project.

$$\mathrm{C}\mathrm{a}\mathrm{l}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n} \mathrm{f}\mathrm{o}\mathrm{r}\mathrm{m}\mathrm{u}\mathrm{l}\mathrm{a}:\mathrm{N}\mathrm{P}\mathrm{V}={\sum }_{\mathrm{t}=0}^{\mathrm{n}}{\displaystyle \frac{\mathrm{C}\mathrm{I}\mathrm{t}-\mathrm{C}\mathrm{O}\mathrm{t}}{(1+\mathrm{i})\mathrm{t}}}$$

where

• NPV represents the net present value;
• CI_t represents the cash inflow in the t-th year;
• CO_t represents the cash outflow in the t-th year;
• i represents the discount rate, that is, the expected minimum rate of return;
• n represents the expected lifespan of the investment project.
• Decision-making principles:

When NPV > 0, it indicates that the actual rate of return of the plan is higher than the required rate of return, and the plan is feasible;

When NPV = 0, it indicates that the actual rate of return of the plan just reaches the required rate of return;

When NPV < 0, it indicates that the actual rate of return of the plan is lower than the required rate of return, and the plan is not feasible.

Based on the data analysis in

Table 3. Calculation table of net present value for photocatalytic reduction of CO_2. Unit: ten thousand yuan.

	Initial Cash Flow	Operating Cash Flow	Terminal Cash Flow	NPV
TCN(NH3)	−2200.01	−6093.04	200.01	−39,562.00
T-CN/ZIS	−2542.05	−5963.94	542.05	−38,981.25
CNBB-3	−2208.66	−6101.53	208.66	−39,622.04
Ta3N5/Bi	−2229.59	−5690.84	229.59	−37,111.17
Ta3N5 cuboid	−2221.86	−6042.75	221.86	−39,268.90
NiOx/Ta3N5	−2222.03	−3163.44	222.03	−21,575.64

, assuming that the project construction period is 0 and the project duration is 10 years, under the condition of a discount rate of 10%, the net present values of all catalysts are shown as negative numbers. This indicates that, from an economic perspective, investment projects using these catalysts for photocatalytic CO₂ reduction are not feasible under current conditions.

4. Influence of Key Factors on Economic Benefits

4.1. Analysis of Influencing Factors

4.1.1. Catalytic Efficiency

The catalytic performance of catalysts plays an extremely important role in chemical reactions and industrial production. Highly efficient catalysts can accelerate the reaction process and increase the reaction yield. In today’s increasingly resource-constrained environment, an improvement in catalyst performance contributes to the efficient utilization and recycling of resources, promoting the sustainable development of the economic society.

4.1.2. Discount Rate

The discount rate plays a crucial role in the calculation of net present value because it determines the magnitude of the present value of future cash flows. A higher discount rate means that the current value of future cash flows is lower, as they are “discounted” less to the present. Conversely, a lower discount rate makes the current value of future cash flows higher.

4.1.3. Depreciation Period

The depreciation period has a significant impact on the net present value. Although depreciation does not directly affect cash flows, it affects costs, expenses, and corporate income tax, thus indirectly affecting cash flows (assuming an income tax rate of 25%). Generally, the longer the depreciation period, the higher the net present value, and the degree of this impact is also closely related to the discount rate. Therefore, the setting of the depreciation period is one of the important considerations in evaluating the economic feasibility of investment projects.

4.1.4. Lighting Conditions

According to the cost analysis results in Table 2, the initial investment cost of the xenon lamp accounts for a relatively large proportion. The photocatalytic reduction of CO₂, as an artificial conversion pathway that simulates natural photosynthesis, has the significant advantage of utilizing solar energy to synthesize high value-added chemicals and fuels under normal temperature and pressure conditions. If sunlight is used as an alternative light source, it can not only significantly reduce the continuous investment cost of the xenon lamp but also markedly decrease the equipment purchase cost. Through calculation, if sunlight is directly used to replace the xenon lamp during the reduction process, the equipment cost can be reduced to 5 million yuan, and at this time, the equipment cost only includes the costs of the reaction kettle and the detection equipment. Considering an annual average sunshine condition of about 2200 h in Hefei, the net present value data shown in the following table are obtained after accounting.

It can be seen from

Table 4. Calculation table of net present value under sunlight illumination. Unit: ten thousand yuan.

	Initial Cash Flow	Operating Cash Flow	Terminal Cash Flow	NPV
TCN(NH3)	−550.01	4.09	50.01	−505.61
T-CN/ZIS	−892.05	33.97	392.05	−532.15
CNBB-3	−558.66	2.12	58.66	−532.00
Ta3N5/Bi	−579.59	97.19	79.59	48.29
Ta3N5 cuboid	−571.86	15.73	71.86	−447.50
NiOx/Ta3N5	−572.03	682.24	72.03	3647.80

that the net present value has been significantly increased under sunlight illumination. It is worth noting that the net present values corresponding to the Ta₃N₅/Bi and NiOx/Ta₃N₅ catalysts have exceeded 0, indicating a certain economic feasibility.

Apart from illumination, any changes in the catalytic performance of the catalyst, the discount rate, the depreciation period, etc., will also affect the costs and benefits of the photoreduction of CO₂ and thus impact its economic feasibility. Next, the following factors will be changed under different lighting conditions to observe the changes in the net present value.

4.2. Analysis of Changing Key Factors Under Different Lighting Conditions

4.2.1. Changing the Performance of the Catalyst

Assume that, with the cost remaining unchanged, the catalytic performance of the catalyst can be continuously improved from the original basis, and the yield can be expanded infinitely.

Through calculation, it is found that under xenon lamp illumination, when the yield is expanded to 2.2 times the original, the net present value corresponding to the catalyst NiOx/Ta₃N₅ has become positive. The change in the net present value of the remaining catalysts with the yield is shown in Figure 3. Under the condition that the catalytic performance of the catalyst can be infinitely improved, when the yield is increased to 110 times the original, the net present values corresponding to the remaining catalysts, except for TCN(NH₃) and CNBB-3, have turned from negative to positive. The net present values corresponding to Ta₃N₅/Bi and T-CN/ZIS turn positive when the yield is expanded to 16 times and 47 times the original, respectively. Overall, the composite catalysts composed of Ta₃N₅ exhibit significant advantages in catalytic efficiency compared with the g-C₃N₄ composite catalysts.

Since the net present values corresponding to Ta₃N₅/Bi and NiOx/Ta₃N₅ have turned positive under sunlight illumination, the focus is on observing the impact of an improving yield on the economic benefits of the photoreduction of CO₂ by the remaining catalysts. As can be seen from Figure 4, when the yield is increased to 2.64 times and 6.15 times the original, the net present values corresponding to the T-CN/ZIS and Ta₃N₅ cuboid catalysts turn positive, respectively. When the yield is increased to about 40 times the original, the net present value corresponding to the TCN(NH₃) turns positive, and only the net present value corresponding to the CNBB-3 catalyst remains negative. At the same time, the net present value of the photocatalytic reduction of CO₂ under xenon lamp illumination is much lower than that under sunlight illumination.

4.2.2. Changing the Discount Rate

By calculating the net present value of the photocatalytic reduction of CO₂ under the discount rate (i) within the range of 3–20%, the following data are obtained. It should be noted that since the net present values corresponding to TCN(NH₃), CNBB-3, and T-CN/ZIS are similar, and their changing trends are the same. In order to better present the changing trends, only T-CN/ZIS and the remaining catalysts are selected for comparison when drawing the graph. The same operation is also adopted when changing the depreciation period.

It can be seen from Figure 5 that under xenon lamp illumination, when the discount rate is increased to 20%, all net present values remain negative. Evidently, the change in the discount rate is not sensitive to the net present value. As can be observed from Figure 6, under sunlight, the net present value shows a downward trend with the increase in the discount rate. Within this range of change, the net present value corresponding to the catalyst NiOx/Ta₃N₅ is greater than 0, and the net present value corresponding to Ta₃N₅/Bi turns negative when the discount rate is increased to 12%. The net present values corresponding to the other catalysts remain negative.

4.2.3. Changing the Depreciation Period

To explore the impact of the equipment service life (i.e., the depreciation period) on the net present value, we set an analysis range from 5 years to 20 years. We calculated the net present value corresponding to each depreciation period within this range and used a line chart to visually present the results.

As shown in Figure 7, with the increase in the depreciation period, the net present values corresponding to the photocatalytic reduction of CO₂ by various catalysts under xenon lamp illumination show a downward trend. According to Figure 8, under sunlight illumination conditions, the net present value does not change much with the increase in the depreciation period. Overall, due to the excessive cost of xenon lamps under xenon lamp illumination, the variation range of the net present value with the depreciation period is greater than that of the net present values corresponding to various catalysts under sunlight illumination with the depreciation period.

5. Conclusions

Under global warming, the photocatalytic reduction of carbon dioxide is one of the important measures for carbon reduction. If industrialization can be achieved, it will be of great significance to society, the economy, the environment, and other aspects. By studying the economic benefits of currently popular nitride-based catalysts in the photocatalytic reduction of CO₂, it is found that their application in the field of CO₂ reduction still faces many challenges and has not yet reached the feasibility standard for commercial application. This is mainly due to the high cost of the existing nitride catalysts, limited catalytic efficiency, and cost issues during the reaction process, with the prominent large-scale cost input of xenon lamps. During the analysis of key factors, replacing xenon lamps with sunlight greatly saves on this part of the investment, making the net present values corresponding to the Ta₃N₅/Bi and NiOx/Ta₃N₅ catalysts positive. However, in practical applications, it is quite difficult to directly use sunlight as the experimental light source. Although nitride-based photocatalytic technology shows a certain potential, many technical bottlenecks still need to be overcome in practical applications. When studying the impact of the catalytic efficiency of catalysts on the net present value, we assumed an ideal state. However, in practical situations, to improve the catalytic efficiency, various technical obstacles need to be overcome. For example, during the large-scale preparation of catalysts, it is difficult to maintain a uniform distribution of active sites, resulting in performance fluctuations among batches. In long-term operation, deactivation phenomena such as coking and poisoning occur, requiring the frequent regeneration or replacement of catalysts, which significantly increases the operation and maintenance costs. Moreover, the mismatch between the mass transfer and heat transfer limitations of the reaction system and the improvement in catalyst activity restricts the room for enhancing the overall efficiency.

In research on the photocatalytic reduction of carbon dioxide, it is recommended to focus on three aspects. First, develop low-cost and high-efficiency catalysts. Increase the R&D investment in new photocatalysts; synthesize new catalysts through interdisciplinary cooperation in materials science, chemical engineering, etc.; and optimize their performance using nanotechnology and surface modification to promote industrialization. Second, reduce the reaction costs, with the utilization of sunlight as the core research direction. Simultaneously, optimize the design of the laboratory xenon lamp system. On the one hand, simulate the solar spectrum with xenon lamps to form the technical experience that can be transferred to natural light scenarios. On the other hand, for special scenarios such as underground spaces and polar scientific research, use the optimized xenon lamp system as a transitional application solution. Its modular design and large-scale production path are both compatible with the core sunlight technology system, thus promoting the commercialization of the technology. Third, optimize the reaction environment. Design a reasonable reaction chamber structure; optimize the gas flow path; precisely control reaction conditions including temperature, pressure, reaction time, etc.; and introduce a real-time monitoring and feedback control mechanism to improve the efficiency and yield of the photocatalytic reduction of CO₂.

During the implementation and analysis of this research, there are inevitably some deficiencies. When discussing the feasibility of relevant content, the research only conducts an in-depth analysis and consideration from the single dimension of economic value. However, it should be noted that the impact of the photocatalytic reduction of CO₂ technology or process is multi-faceted, and social benefits are an extremely important aspect. Social benefits cover a wide range, including the impact on environmental quality improvement, possible changes in the social employment structure, and potential effects on public health levels. The difficulty in quantifying the social benefits of the photocatalytic reduction of CO₂ may lead to an incomplete and inaccurate overall feasibility assessment.