Search Results (146)

In this study, we present the synthesis of TiO₂ nanomaterials doped with different mol% cobalt, prepared by the sol–gel method for CO₂ reduction using UV light. The nanomaterials were calcined at 400 °C for 4 h. Characterization of the nanomaterials was performed using XRD-Rietveld refinement, XPS, Raman spectroscopy, diffuse reflectance spectroscopy (DRS), SEM-EDS, TEM-HRTEM, BET area, photoluminescence, and electrochemical techniques. The results show that the incorporation of cobalt into TiO₂ modifies the structural properties, binding energies, and oxygen vacancy generation, it undergoes a shift towards the visible region, the recombination of charge carriers decreases, and the BET area is slightly modified. The photoreduction of CO₂ with the highest production of methane and ethane is with 1% mol% of cobalt in TiO₂, exhibiting values 3 and 14 times higher with respect to TiO₂, which is attributed to the efficiency in the separation of photogenerated species (e⁻/h⁺) as a consequence of the generation of energetic states that function as an electron trap and thus improve the photocatalytic activity for the photoreduction of CO₂. Full article

Photocatalytic reduction of CO₂ into value-added chemicals offers a sustainable route to mitigate greenhouse gas emissions while producing renewable fuels. However, conventional TiO₂-based systems suffer from limited visible-light activity and inefficient reactor configurations. Here, we developed electrospun polyacrylonitrile (PAN) membranes embedded with TiO₂-Cu₂O heterojunction nanoparticles and integrated them into a custom crossflow photocatalytic membrane reactor. The reactor employed bifacial illumination using a solar simulator (front) and a xenon/mercury lamp (back), each calibrated to 1 Sun (100 mW·cm⁻²). Membrane morphology was characterized by SEM, and chemical composition was confirmed by XPS. Photocatalytic performance was evaluated in CO₂-saturated 0.5 M potassium bicarbonate solution under continuous flow. The PAN/ TiO₂-Cu₂O membrane exhibited a methanol production rate of approximately 300 μmol·g⁻¹·h⁻¹ under dual-light illumination, outperforming single illumination, PAN-TiO₂, and PAN controls. Enhanced activity is attributed to extended visible-light absorption, improved charge separation at the TiO₂-Cu₂O heterojunction, and optimized photon flux through bifacial illumination. The electrospun architecture provided high surface area and porosity, facilitating CO₂ adsorption and catalyst dispersion. Combining heterojunction engineering with bifacial reactor design significantly improves solar-driven CO₂ conversion. This approach offers a scalable pathway for integrating photocatalysis and membrane technology into sustainable fuel synthesis. Full article

In this study, we report a reproducible in situ photochemical method for the simultaneous synthesis of metallic and hybrid metal/metal oxide nanoparticles (NPs) within a UV–curable polymer matrix. A series of epoxy diacrylate-based formulations (BEA) was prepared, consisting of Epoxy diacrylate, Di(Ethylene glycol)ethyl ether acrylate (DEGEEA), and Phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO), which served as a Type I photoinitiator. These formulations were designed to enable the simultaneous photopolymerization and photoreduction of metal precursors at various Ag⁺/Co²⁺ ratios, resulting in nanocomposites containing in situ-formed Ag NPs, cobalt oxide NPs, and hybrid Ag–Co₃O₄ nanostructures. The photochemical, magnetic, and dielectric properties of the resulting nanocomposites were evaluated in comparison with those of the pure polymer using UV–Vis and Fourier Transform Infrared Spectroscopy (FT-IR), Photo-Differential Scanning Calorimetry (Photo-DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Impedance Analysis, and Vibrating Sample Magnetometry (VSM). Photo-DSC studies revealed that the highest conversion values were obtained for the BEA-Ag₁Co₁, BEA-Co, and BEA-Ag₁Co₂ samples, demonstrating that the presence of Co₃O₄ NPs enhances polymerization efficiency because of cobalt species participating in redox-assisted radical generation under UV irradiation, increasing the number of initiating radicals and leading to faster curing and higher final conversion. On the other hand, the Ag NPs, due to the SPR band formation at around 400 nm, compete with photoinitiator absorbance and result in a gradual decrease in conversion values. Crystal structures of the NPs were confirmed by XRD analyses. The dielectric and magnetic characteristics of the nanocomposites suggest potential applicability in energy-storage systems, electromagnetic interference mitigation, radar-absorbing materials, and related multifunctional electronic applications. Full article

With the dual challenges of global energy scarcity and worsening environmental issues, the efficient and selective conversion of CO₂ into CH₄-an environmentally friendly fuel with high energy density—offers considerable application potential. In this study, a 2D-Cu₂O/carbon nitride (2D-Cu₂O/CN) heterojunction catalyst was successfully prepared. Notably, 2D-Cu₂O/CN shows enhanced light absorption capacity, reduced charge-transfer resistance, and efficient separation of photogenerated electron–hole pairs. It exhibits a CH₄ yield of 14.1 μmol·g⁻¹·h⁻¹, 4-fold higher than that of CN. This study provides a feasible approach for the design of high-efficiency photocatalysts for CO₂ reduction to CH₄. Full article

The increasing atmospheric concentration of CO₂ is a major contributor to global climate change, underscoring the urgent need for effective strategies to convert CO₂ into value-added products. In this sense, a composite was successfully synthesized by combining clinoptilolite zeolite (CZ) with varying amounts of copper oxide (CuO-1% and 10%) for CO₂ photoreduction. The composites were characterized using insightful techniques, including XRD, nitrogen physisorption, DRS, and SEM. The results confirmed the incorporation and dispersion of CuO within the CZ support. The XRD analysis revealed characteristic crystalline CuO peaks. Despite the low surface area (<15 m²·g⁻¹) and macroporous nature of the samples, EDS imaging revealed an effective and homogeneous dispersion of CuO, indicating efficient surface distribution. UV–Vis diffuse reflectance spectroscopy revealed band gap energies of 3.30 eV (CZ), 3.38 eV (1%-CuO/CZ), and 1.75 eV (10%-CuO/CZ), highlighting the pronounced electronic changes resulting from CuO incorporation. Photocatalytic tests conducted under UVC irradiation (λ = 254 nm) revealed that 10%-CuO/CZ exhibited the highest CO and CH₄ production, 35 µmol·g⁻¹ and 3.6 µmol·g⁻¹, respectively. The composite also delivered the highest CO productivity (5.91 µmol·g⁻¹·h⁻¹), approximately 3.5 times that of pristine CZ, in addition to achieving the highest CH₄ productivity (0.60 µmol·g⁻¹·h⁻¹). Furthermore, turnover frequency (TOF) analysis normalized per Cu site revealed that CuO incorporation not only enhances total productivity but also improves the intrinsic catalytic efficiency of the active copper centers. Overall, the synthesized composites demonstrate promising potential for CO₂ photoreduction, driven by synergistic structural, electronic, and morphological features. Full article

The development of versatile photocatalysts is crucial for comprehensive solutions to the intertwined challenges of the energy crisis and environmental pollution. This study presents a novel Bi₃TiNbO₉/Bi₂MoO₆ (BTNO/BMO) heterojunction fabricated via a solvothermal method. Advanced characterization techniques verified the successful synthesis of the as-integrated BTNO/BMO heterostructure. The BTNO/BMO composite exhibited superior performance in multiple applications: efficient degradation of tetracycline reaching 90.2%, removal of gaseous nitric oxide (NO), and photocatalytic reduction of carbon dioxide (CO₂) to carbon monoxide (CO) with a yield of 51.3 μmol·g⁻¹. The constructed Type-II heterojunction demonstrated a remarkable ability to suppress charge recombination, thereby significantly enhancing the photocatalytic activity. This work highlights the dual-functional capability of the BTNO/BMO heterojunction for simultaneous environmental purification and fuel production, providing a promising material platform and a strategic design concept for sustainable technological development. Full article

The photocatalytic reduction of CO₂ in aqueous media offers a sustainable route for solar-to-fuel conversion, yet remains challenged by CO₂’s thermodynamic stability and kinetic inertness, low solubility, and competitive hydrogen evolution. Here, we investigate the interplay between ionic liquids (ILs), photocatalyst supports, and additive composition in directing product selectivity among CO, CH₄, and H₂. Using imidazolium acetate as a benchmark, we demonstrate that ILs not only pre-activate CO₂ but can also undergo decomposition pathways under illumination, notably Kolbe-type reactions leading to methane formation from acetate rather than from CO₂. Comparative studies of Pd-decorated TiO₂ and g-C₃N₄ nanosheets reveal distinct behaviors driven by their interfacial interactions with the imidazolim-based ionic liquid: weak interaction with TiO₂ strongly promotes hydrogen evolution, whereas strong coupling with g-C₃N₄ synergizes with C₁C₄ImOAc to trigger acetate-derived Kolbe reactivity. The systematic evaluation of alternative salts confirms the determinant role of anion basicity and medium-pH-basic anions facilitate CO₂ activation, whereas weakly basic or non-coordinating anions favor water splitting. Overall, these results clarify the dual role of ionic liquids as both CO₂ activators and sacrificial agents, and highlight design principles for improving product selectivity and efficiency in aqueous CO₂ photoreduction systems. Full article

Photocatalytic CO₂ reduction holds great potential for sustainable solar fuel production, yet its practical application is often limited by inefficient charge separation and poor product selectivity. The photothermal effect presents a viable strategy to address these challenges by reducing activation energies and accelerating reaction kinetics. In this work, we report a rationally designed CN-B/Ti₃C₂ heterojunction that effectively leverages photothermal promotion for enhanced CO₂ reduction. The black carbon nitride (CN-B) framework, synthesized via a one-step calcination of urea and Phloxine B, exhibits outstanding photothermal conversion, reaching 131.4 °C under 300 mW cm⁻² illumination, which facilitates CO₂ adsorption and charge separation. Coupled with Ti₃C₂ MXene, the optimized composite (3:1) achieves remarkable CO and CH₄ production rates of 80.21 and 35.13 μmol g⁻¹ h⁻¹, respectively, without any cocatalyst—representing a 2.9-fold and 8.8-fold enhancement over CN-B and g-C₃N₄ in CO yield. Mechanistic studies reveal that the improved performance stems from synergistic effects: a built-in electric field prolongs charge carrier lifetime (3.15 ns) and reduces interfacial resistance, while localized heating under full-spectrum light further promotes CO₂ activation. In situ Fourier transform infrared (FTIR) spectroscopy confirms the accelerated formation of key intermediates (*COOH and *CO). The catalyst also maintains excellent stability over 24 h. This study demonstrates the promise of combining photothermal effects with heterojunction engineering for efficient and durable CO₂ photoreduction. Full article

The photocatalytic reduction of carbon dioxide (CO₂) into energy-dense fuels using visible light provides a sustainable approach for solar-to-chemical energy transformation. Among the diverse metal molecular systems developed, ruthenium (II) (Ru(II)) complexes have emerged as promising catalysts due to their superior redox properties, strong visible light absorption, and customizable ligand structures. This review explores recent advances in Ru(II)-catalyzed CO₂ photoreduction, with particular attention given to catalyst design strategies, mechanistic pathways, and system integration methodologies. Key configurations, including photosensitizer/catalyst (PS/Cat) mixed systems, covalently bonded dyads, and hybrid/supramolecular frameworks, are evaluated in terms of efficiency, turnover numbers (TON), and selectivity. A critical analysis of challenges such as competing H₂ generation, inefficient charge transfer, and limited long-term stability is presented. Emerging trends toward the use of pincer ligands, transition metal integration, and self-photosensitizing frameworks are discussed as potential approaches for improving efficiency. Overall, this review offers insights into the structural and mechanistic features driving CO₂ photoreduction and provides perspectives for the rational design of next-generation Ru-based photocatalytic systems for efficient solar CO₂ conversion and the photocatalytic reduction of carbon dioxide (CO₂) into energy-dense fuels using visible light. Full article

Photocatalytic conversion of CO₂ to hydrocarbon fuels offers a promising pathway for sustainable renewable energy production. In this study, a ZnO/ZnFe₂O₄ composite featuring a Type-II heterojunction was synthesized through a facile one-step hydrothermal approach, significantly enhancing visible-light-driven CO₂ reduction activity. The optimized catalyst exhibits CH₄ and CO production rates that are 3.3 and 4.9 times higher, respectively, than those of pristine ZnFe₂O₄ over 6 h. This significant enhancement in photocatalytic performance is attributed to the Type-II band alignment, which not only broadens light absorption but also greatly promotes efficient charge separation. It is corroborated by a series of experimental evidence: a two-fold enhancement in photocurrent response, a 15.1% reduction in PL intensity, decreased electrochemical impedance, and an extended charge carrier lifetime. Furthermore, in situ FTIR spectroscopy confirms that the heterojunction facilitates the formation of key intermediates (specifically *COOH and HCOO⁻). This study highlights the importance of precise interface design based on a Type-II heterojunction in heterostructured composite catalysts and provides mechanistic insights for developing highly efficient CO₂ photoreduction systems. Full article

Elucidating the mechanisms of CO₂ photocatalytic conversion systems is crucial for tackling the challenges of carbon neutrality. In this study, a series of Ag@g-C₃N₄ photocatalysts were constructed with metal particle size modulation as the core strategy to systematically reveal the modulation mechanism of Ag nanoparticles (Ag NPs) size variation on the selectivity of CO₂ photoreduction products. Systematic characterizations revealed that increasing Ag size enhanced visible light absorption, promoted charge separation, and improved CH₄ selectivity. Photocatalytic tests showed Ag_3.0%@CN achieved optimal activity and electron utilization. Energy band analyses indicated that Ag modification preserved favorable conduction band positions while increasing donor capacity. Further density-functional theory (DFT) calculations reveal that Ag NPs size variations significantly affect the adsorption stability and conversion energy barriers of intermediates such as *COOH, CO and CHO, with small-sized Ag₇ NPs favoring the CO pathway, while large-sized Ag NPs stabilize the key intermediates and drive the reaction towards the CH₄ pathway evolution. The experimental and theoretical results corroborate each other and clarify the dominant role of Ag NPs size in regulating the reaction path between CO and CH₄. This study provides mechanistic guidance for the selective regulation of the multi-electron reduction pathway, which is of great significance for the construction of efficient and highly selective CO₂ photocatalytic systems. Full article

In recent decades, photocatalysis has received huge attention as a way to address the main environmental challenges affecting planet Earth. Among these, the control of CO₂ emission and its concentration in the atmosphere, as one of the greenhouse gases causing global warming, is of primary importance. This study focuses on the hydrothermal preparation of doped Ba and Ca-based titanates as efficient photocatalytic materials for CO₂ photoreduction under solar light. The materials were characterized by SEM-EDX, XPS, FT-IR ATR, DRS, CHNS, XRD, and N₂ physisorption analyses, and tested for gas-phase methane production from the target reaction. According to the results, the visible light harvesting properties were significantly improved with C and N doping, where glucose and a bio-based chitosan acted as the C and C+N sources, respectively. In particular, C-Ba-based titanate (CBaT) indicated the highest CH₄ productivity, 2.3 µmol/g_cat, against zero activity of the corresponding bare titanate structure, BaT. The larger surface area and pore volume, as well as its narrower band gap, are suggested as the major reasons for the promising performance of CBaT. This work provides new insights for the facile fabrication of efficient photoactive perovskite materials with the aim of CO₂-to-CH₄ photoreduction under solar light. Full article

Constructing heterojunction photocatalysts with efficient interfacial charge transfer is critical for solar-driven hydrogen evolution. In this study, a highly dispersed MoS₂/g-C₃N₄ composite was successfully synthesized via a stirring-assisted hydrothermal in situ growth strategy. The introduction of stirring during synthesis significantly enhanced the uniform dispersion of MoS₂ nanosheets and exposed abundant edge sites, leading to well-integrated heterojunctions with enhanced interfacial contact. Comprehensive structural and photoelectronic characterizations (XRD, SEM, TEM, EDS mapping, UV–Vis, TRPL, EIS, EPR) confirmed that the composite exhibited improved visible-light absorption, accelerated charge separation, and suppressed recombination. Under simulated solar irradiation with triethanolamine (TEOA) as a sacrificial agent, the optimized 24% MoS₂/g-C₃N₄-S catalyst achieved a high hydrogen evolution rate of 14.33 mmol·g⁻¹·h⁻¹ at a catalyst loading of 3.2 mg, significantly outperforming the unstirred and pristine components, and demonstrating excellent cycling stability. Mechanistic studies revealed that the performance enhancement is attributed to the synergistic effects of Type-II heterojunction formation and edge-site-rich MoS₂ co-catalysis. This work provides a scalable approach for non-noble metal interface engineering and offers insight into the design of efficient and durable photocatalysts for solar hydrogen production. Full article

Developing photocatalysts with both high efficiency and reaction pathway selectivity is essential for achieving efficient and sustainable CO₂ conversion. By incorporating sulphur vacancies into MoS₂, an S-scheme heterojunction photocatalyst (MoS₂-SVs/g-C₃N₄) was developed, achieving efficient and selective CO₂ photoreduction to CH₃OH. The structural and photoelectronic characterisation of the system shows that the heterogeneous interface between MoS₂ and g-C₃N₄ is in close contact. The introduction of SVs effectively modulates the electronic structure and surface activity of MoS₂, which in turn enhances the CO₂ reduction performance. Optical and electronic structure analyses reveal that the heterojunction promotes favourable band alignment and interfacial electric potential gradients, which together suppress charge recombination and enhance directional carrier separation. Under irradiation, the MoS₂-SVs/g-C₃N₄ photocatalyst exhibited outstanding photocatalytic CH₃OH production with a yield of 10.06 μmol·h⁻¹·g⁻¹, significantly surpassing the performance of control samples while demonstrating excellent product selectivity and remarkable stability. Mechanistic studies further verify that vacancy-induced energy band modulation with Fermi energy level enhancement significantly reduces the multi-electron transfer barrier, thus preferentially driving the CH₃OH generation pathway. This work proposes a universal structural design strategy that synergistically coordinates vacancy engineering with band structure modulation, establishing both theoretical principles and practical methodologies for developing selective multi-electron CO₂ reduction systems. Full article

Over efficient photocatalysts, CO₂ photoreduction typically converts CO₂ into low-carbon chemicals, which serve as raw materials for downstream synthesis processes. Here, an efficient composite photocatalyst heterojunction (Cu₂O-u/g-C₃N₄) has been fabricated to reduce CO₂. Graphitic carbon nitride (g-C₃N₄) was synthesized via thermal polymerization of urea at 550 °C, while pre-dispersed Cu₂O derived from urea pyrolysis (Cu₂O-u) was prepared by thermal reduction of urea and CuCl₂·2H₂O at 180 °C. The heterojunction Cu₂O-u/g-C₃N₄ was subsequently constructed through hydrothermal treatment at 180 °C. This heterojunction exhibited a bandgap of 2.10 eV, with dual optical absorption edges at 485 nm and above 800 nm, enabling efficient harvesting of solar light. Under 175 W mercury lamp irradiation, the heterojunction catalyzed liquid-phase CO₂ photoreduction to formic acid, acetic acid, and methanol. Its formic acid production activity surpassed that of pristine g-C₃N₄ by 3.14-fold and TiO₂ by 8.72-fold. Reaction media, hole scavengers, and reaction duration modulated product selectivity. In acetonitrile/isopropanol systems, formic acid and acetic acid production reached 579.4 and 582.8 μmol·h⁻¹·g_cat⁻¹. Conversely, in water/triethanolamine systems, methanol production reached 3061.6 μmol·h⁻¹·g_cat⁻¹, with 94.79% of the initial conversion retained after three cycles. Finally, this work ends with the conclusions of the CO₂ photocatalytic reduction to formic acid, acetic acid, and methanol, and recommends prospects for future research. Full article