Search Results (133)

Electrochemical CO₂ reduction reaction through utilizing renewable electricity under mild conditions is a promising pathway toward achieving carbon neutrality. In this work, we designed a tubular graphyne functionalized with isolated Co single atom and lowered the activation energy barrier of its rate-determining step to as low as 0.46 eV. The catalytic performance was systematically evaluated through density functional theory calculations. Compared with the planar graphyne functionalized with isolated Co single atom, the tubular one not only significantly improves the utilization efficiency of Co single atoms by exposing them more thoroughly, but also increases the catalytic activity of Co single atom by enhancing electron density of states at the Fermi level, which causes a higher level of activation state for the adsorbed CO₂ molecules. Furthermore, it brought about the CO₂-to-CH₄ reduction reaction pathway, resulting in remarkable catalytic activity and high methane selectivity. Our study demonstrates the efficacy of curvature engineering in enhancing the intrinsic activity of single-atom catalysts, offering a novel strategy for designing advanced carbon cycle catalysts. Full article

Single-atom catalysts are highly efficient electrocatalysts for water splitting with exceptional atomic utilization, but atomic aggregation can impair their catalytic performance. To address this challenge, a Fe-Co-Ni single-atom bifunctional catalyst supported on nitrogen-doped graphene oxide was designed and employed for overall water splitting in alkaline electrolyte. The catalyst’s composition, structure, and morphology were systematically characterized using XRD, XPS, SEM, and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Electrochemical evaluations were performed to assess its activity and stability toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The results demonstrate that strong metal-nonmetal interactions between the Fe, Co and Ni single atoms and the nitrogen-doped graphene oxide support facilitate stable and uniform anchoring of the metal centers on the wrinkled carbon framework. The total metal loading reaches approximately 6.78 wt%, ensuring a high density of accessible active sites. Furthermore, synergistic electronic coupling among the Fe, Co, and Ni centers enhances charge transfer kinetics and modulates the D-band electronic states of the metal atoms. This effect weakens the adsorption strength of hydrogen and oxygen-containing intermediates, thus promoting faster reaction kinetics for both HER and OER. Consequently, the FeCoNi/CNG catalyst delivers low overpotentials of 77 mV for HER and 355 mV for OER at a current density of 10 mA cm⁻² in alkaline conditions. When integrated into an alkaline water electrolyzer, the system achieves a cell voltage of only 1.68 V to attain a current density of 10 mA cm⁻², underscoring its outstanding bifunctional catalytic performance. Full article

Ammonia serves as a critical industrial feedstock and a potential carbon-free energy carrier. However, its conventional synthesis method (the Haber–Bosch process) suffers from high energy consumption and substantial carbon emissions. The electrochemical nitrate reduction reaction (eNO₃RR) has emerged as a promising alternative pathway, capable of converting nitrate pollutants in water into high-value ammonia under mild conditions, enabling green synthesis while offering dual benefits of environmental remediation and energy conversion. Single-atom catalysts (SACs), with their maximal atom utilization efficiency, well-defined active sites, and highly tunable electronic structures, have demonstrated exceptional catalytic performance and selectivity in eNO₃RR. This review systematically summarizes recent advances of SACs in eNO₃RR, with a focus on reaction mechanisms, advanced in situ characterization techniques, theoretical calculation, and the catalytic behavior and structure–activity relationships of various non-noble metal centers (e.g., Cu, Fe, Co). Key strategies for enhancing SACs performance are elaborated, alongside an analysis of microenvironmental influences such as electrolyte composition, pH, and potential. Finally, we outlines current challenges in material design, dynamic active site identification, and the industrial application of SACs, and propose future research directions aimed at facilitating the practical implementation of eNO₃RR technology and contributing to the establishment of a sustainable ammonia economy. Full article

The reverse water–gas shift (RWGS) reaction efficiently converts CO₂ to CO, with vital applications in carbon emission reduction and Fischer-Tropsch chemical production. This study used density functional theory (DFT) to investigate CO₂ adsorption and activation on CeO₂, oxygen-vacancy CeO₂ (CeO_2−x), and single-atom Ni-loaded CeO₂ (Ni/CeO₂). Adsorption energy analysis indicates that CO₂ preferentially adsorbs at the intermediate oxygen sites on CeO₂ and Ni/CeO₂, but on CeO_2−x, it preferentially adsorbs at the oxygen vacancies. Mulliken charge and band gap results indicate that CeO_2−x and Ni/CeO₂ exhibit higher activity than pure CeO₂. Density of states studies indicate that CeO₂, CeO_2−x, and Ni/CeO₂ can activate CO₂ to varying degrees; strong hybridization between Ni’s d-orbitals and CO₂’s O p-orbitals is key to Ni/CeO₂’s high activity. Mechanistically, CeO_2−x follows the RWGS redox mechanism, while Ni/CeO₂ follows the formate-associated mechanism. This work innovatively clarifies differential CO₂ adsorption-activation by vacancies and Ni in CeO₂-based catalysts, providing a theoretical basis for RWGS catalyst design and supporting low-energy carbon conversion development. Full article

The renewable-energy-powered electrocatalytic CO₂ reduction reaction (CO₂RR) efficiently converts CO₂ into high-value chemicals and fuels, offering a promising approach to addressing environmental and energy sustainability challenges. This process is of immense significance for constructing a sustainable artificial carbon cycle. Cu-based catalysts exhibit remarkable catalytic activity and broad product selectivity in CO₂RR, which can be attributed to their excellent electrical conductivity, moderate adsorption energy, and unique electronic structure. This review comprehensively summarizes the advantages, practical applications, and mechanistic insights of Cu-based catalysts in CO₂RR, with a systematic based on recent advances in tuning strategies via electronic effects and structural design. Specifically, it emphasizes the influence of electronic structure tuning (electron-donating/-withdrawing effects and steric hindrance effects), active center tuning (single-atom catalysts, heterogeneous synergetic effects, and polymer modification), and surface structure (morphology effect, valence-state effect, and crystalline-facet effect) influences on catalytic performance. By rationally designing the catalyst structure, the adsorption behavior of reaction intermediates can be effectively regulated, thereby enabling the highly selective generation of target products. The objective of this paper is to provide a theoretical framework and actionable strategies for the structural design and catalytic performance optimization of Cu-based catalysts, with the ultimate goal of promoting the development and practical application of efficient CO₂RR catalytic systems. Full article

The development of high-efficiency and stable oxygen evolution reaction (OER) electrocatalysts is crucial for sustainable hydrogen production via water splitting. Single-atom catalysts (SACs) represent a promising direction, yet their performance heavily relies on the support material. Herein, we report a highly active OER catalyst comprising ruthenium (Ru) species supported on Fe-doped nickel carbonate hydroxide (NFCH) grown on nickel foam (NF). The NFCH support, synthesized via a hydrothermal method, possesses a high specific surface area and excellent electrical conductivity. The incorporation of carbonate anions (CO₃²⁻) enhances structural stability and interfacial hydrophilicity. Ru was subsequently decorated onto NFCH via electrodeposition to form the NFCH-Ru_x series (where x denotes the mmol amount of Ru precursor). The optimized NFCH-Ru₃ catalyst exhibits outstanding OER performance in 1 M KOH, requiring a low overpotential of only 220 mV to achieve a current density of 10 mA cm⁻², with a small Tafel slope of 40.92 mV dec⁻¹. Furthermore, it demonstrates remarkable durability with negligible activity loss (2.9%) after 12 h of continuous operation, outperforming many recently reported non-precious metal-based catalysts. This work highlights the potential of metal carbonate hydroxides as superior supports for developing high-performance OER electrocatalysts. Full article

This research seeks to investigate extremely efficient catalysts for the nitrogen reduction process (NRR), utilizing machine learning (ML)-aided density functional theory (DFT) computations. Specifically, we investigate dual transition metal atoms anchored on hexagonal nitrogen-doped graphene (TM₁-TM₂@N₆G) as prospective high-activity catalysts for the NRR. The findings indicate that the synergistic effect of dual transition metal atoms in the TM₁-TM₂@N₆G catalyst overcomes the intrinsic constraints of the linear relationship among intermediates, facilitating the activation and adsorption of N₂, thereby exhibiting significant potential for ammonia synthesis through N₂ reduction. Particularly, four catalysts screened by ML and DFT exhibit good stability and excellent selectivity and activation towards N₂. Among them, the catalysts Ti-Cr@N₆G, Ti-Mo@N₆G, and Ti-Pd@N₆G possess two reaction pathways with minimum reaction energies of 0.55 eV, 0.50 eV, and 0.40 eV, respectively. Remarkably, Ti-Co@N₆G, which features a single reaction pathway, exhibits a reaction energy lower than 0.05 eV, allowing the NRR to proceed spontaneously. It is noteworthy that incorporating ML into DFT calculations facilitates the rapid screening of all transition metal combinations, significantly accelerating the research on catalytic performance and optimizing the selection of catalysts. Full article

Single-atom catalysts supported by two-dimensional materials have been widely used in the electrochemical CO₂ reduction reaction (CO₂RR). Defects are inevitably generated during the preparation of two-dimensional materials. In this study, six Fe–N₄-doped graphene catalysts (CAT1–CAT6) containing single carbon vacancy defects were designed and calculated using density functional theory (DFT) calculations. The stability, catalytic activity and product selectivity of these catalysts for CO₂RR to C₁ products CO, HCOOH, CH₃OH and CH₄ were discussed and compared with the defect-free Fe−N₄-doped graphene catalyst (CAT0). The results show that CAT1–CAT6 all exhibit excellent thermodynamic and electrochemical stabilities. The possible reaction pathways for CO₂ reduction to different C₁ products were systematically investigated. The CAT2, CAT3 and CAT6 exhibit high selectivity for HCOOH, whereas the products of CAT1, CAT4 and CAT5 are HCOOH, CH₃OH and CH₄, the same as those of CAT0. Moreover, these six catalysts more effectively suppress the competing hydrogen evolution reaction (HER) compared to CAT0, indicating that the defect improves the catalytic selectivity of CO₂RR. Among all of the catalysts, CAT2 demonstrates the most prominent catalytic activity and selectivity toward the CO₂ reduction reaction (CO₂RR). The large distortion of Fe−N₄ in *HCOO with CAT2 contributes to the lower limiting potential U_L. We hope that the finding that the large distortion of Fe−N₄ could lower the limiting potential will provide theoretical insights for the design of more efficient CO₂RR electrocatalysts. Full article

Carbon dioxide is naturally present in the Earth’s atmosphere and plays a role in regulating and balancing the planet’s temperature. However, due to various human activities, the amount of carbon dioxide is increasing beyond safe limits, disrupting the Earth’s natural temperature regulation system. Today, CO₂ is the most prevalent greenhouse gas; as its concentration rises, significant climate change occurs. Therefore, there is a need to utilize anthropogenically released carbon dioxide in valuable fuels, such as formic acid (HCOOH). Single-atom catalysts are widely used, where a single metal atom is anchored on a surface to catalyze chemical reactions. In this study, we investigated the potential of Cu@Phosphorene as a single-atom catalyst (SAC) for CO₂ reduction using quantum chemical calculations. All computations for Cu@Phosphorene were performed using density functional theory (DFT). Mechanistic studies were conducted for both bimolecular and termolecular pathways. The bimolecular mechanism involves one CO₂ and one H₂ molecule adsorbing on the surface, while the termolecular mechanism involves two CO₂ molecules adsorbing first, followed by H₂. Results indicate that the termolecular mechanism is preferred for formic acid formation due to its lower activation energy. Further analysis included charge transfer assessment via NBO, and interactions between the substrate, phosphorene, and the Cu atom were confirmed using quantum theory of atoms in molecules (QTAIM) and non-covalent interactions (NCI) analysis. Ab initio molecular dynamics (AIMD) calculations examined the temperature stability of the catalytic complex. Overall, Cu@Phosphorene appears to be an effective catalyst for converting CO₂ to formic acid and remains stable at higher temperatures, supporting efforts to mitigate climate change. Full article

Carbon monoxide (CO) is a major toxic gas emitted from vehicle exhaust, industrial processes, and incomplete fuel combustion, posing serious environmental and health risks. Catalytic oxidation of CO into less harmful CO₂ is an effective strategy to reduce these emissions. In this study, we investigated the catalytic performance of platinum (Pt) single atoms doped on C₃N monolayers with various vacancy defects, including single carbon (C_V) and nitrogen (N_V) vacancies, using density functional theory (DFT) calculations. Our results demonstrate that Pt@N_V-C₃N exhibited the most favorable catalytic properties, with the highest O₂ adsorption energy (−3.07 eV). This performance significantly outperforms Pt atoms doped at other vacancies. It can be attributed to the strong binding between Pt and nitrogen vacancies, which contributes to its excellent resistance to Pt aggregation. CO oxidation on Pt@N_V-C₃N proceeds via the Eley–Rideal (ER2) mechanism with a low activation barrier of 0.41 eV for the rate-determining step, indicating high catalytic efficiency at low temperatures. These findings suggest that Pt@N_V-C₃N is a promising candidate for CO oxidation, contributing to developing cost-effective and environmentally sustainable catalysts. The strong binding of Pt atoms to the nitrogen vacancies prevents aggregation, ensuring the stability and durability of the catalyst. The kinetic modeling further revealed that the ER2 mechanism offers the highest reaction rate constants over a wide temperature range (273–700 K). The low activation energy barrier also facilitates CO oxidation at lower temperatures, addressing critical challenges in automotive and industrial pollution control. This study provides valuable theoretical insights for designing advanced single-atom catalysts for environmental remediation applications. Full article

Single-atom catalysts (SACs) have emerged as highly promising catalytic materials for the hydrogen evolution reaction (HER), attributed to their maximal atomic utilization efficiency and unique electronic configurations. Many structure parameters can influence the catalytic performance of SACs for HER, and the intrinsic advantages of SACs for HER still need to be summarized. This review systematically summarizes recent advances in SACs for HER. It discusses various types of SACs (including those based on Pt, Co, Ru, Ni, Cu, and other metals) applied in HER, and elaborates the critical factors influencing catalytic performance—specifically, the supports, coordination environments, and synergistic effects of these SACs. Furthermore, current research challenges and future perspectives in this rapidly developing field are also outlined. Full article

The electrochemical reduction of carbon monoxide (COER) offers a promising route for generating value-added multi-carbon (C₂₊) products, such as ethanol, but achieving high catalytic performance remains a significant challenge. Herein, we performed comprehensive density functional theory (DFT) computations to evaluate CO-to-ethanol conversion on single metal atoms anchored on graphitic carbon nitride (TM/g–CN). We showed that these metal atoms stably coordinate with edge N sites of g–CN to form active catalytic centers. Screening 20 TM/g–CN candidates, we identified V/g–CN and Zn/g–CN as optimal catalysts: both exhibit low free-energy barriers (<0.50 eV) for the key ^*CO hydrogenation steps and facilitate C–C coupling via an Eley–Rideal mechanism with a negligible kinetic barrier (~0.10 eV) to yield ethanol at low limiting potentials, which explains their superior COER performance. An analysis of d-band centers, charge transfer, and bonding–antibonding orbital distributions revealed the origin of their activity. This work provides theoretical insights and useful guidelines for designing high-performance single-atom COER catalysts. Full article

Hydroformylation is one of the most widely applied homogeneous catalytic processes in the chemical industry, constituting the predominant manufacturing platform for aldehyde synthesis at commercial scales. Nevertheless, hydroformylation shares with traditional homogeneous catalysis the inherent limitation of difficult catalyst recovery and recycling. Developing heterogeneous catalysts for such reactions is thus critically needed. Herein, a stable nitrogen-rich covalent triazine framework (CTF) was synthesized via a mild Friedel–Crafts alkylation method and employed as a support for Rh single-atom catalysts (Rh/CTF-TPA). In the hydroformylation of 1-decene, the Rh/CTF-TPA catalyst exhibits an exceptional reaction efficiency (TOF > 1900 h⁻¹), outperforming the homogeneous Rh(CO)₂(acac). Experimental and characterization results revealed that the CTF support enhances catalytic performance through two key mechanisms: (1) strong enrichment of reactants within its special structure, and (2) efficient dispersion of Rh single-atom sites stabilized by abundant nitrogen coordination. This work demonstrates a rational design strategy for heterogeneous hydroformylation catalysts by leveraging nitrogen-rich porous frameworks to synergistically optimize metal anchoring and reactant enrichment, offering a promising alternative to conventional homogeneous systems. Full article

A “thermal-annealing vacancy-filling” synthesis strategy was developed to engineer cobalt single-atom catalysts (Co-MoS₂/RGO) for exceptional hydrogen evolution reaction (HER) performance. By anchoring atomic Co onto Frenkel defect-engineered MoS₂ nanosheets supported by reduced graphene oxide (RGO), we achieved simultaneous optimization of catalytic stability, electrical conductivity, and active site accessibility. The optimized Co₃-MoS₂/RGO hybrid demonstrates remarkable alkaline HER activity, requiring only 94.0 mV overpotential to achieve 10 mA cm⁻² current density while maintaining excellent durability over extended operation. The atomically dispersed Co promoted HER kinetics through electronic structure modulation of MoS₂ basal planes, creation of catalytic active centers, and defect-mediated synergies. The RGO further contributed to performance enhancement by preventing nanosheet aggregation, facilitating charge transfer, and exposing active sites. This defect engineering strategy provides a facile method for developing cost-effective, stable, and high-performance electrocatalysts for sustainable hydrogen production. Full article

Ammonia (NH₃) is a crucial feedstock in chemical manufacturing. The electrocatalytic NO reduction reaction (eNORR) to NH₃ represents a promising alternative method for the green production of NH₃ and for environmental management. This study presents a comprehensive investigation of eNORR properties of single transition metal atoms deposited on WS₂ nanosheets (TM@WS₂). Our results indicate that 19 single TM atoms exhibit strong thermal stability. Among these, five specific TM@WS₂ catalysts—Ti, Mn, Co, Zr, and Hf—demonstrate remarkable eNORR activity, with limiting potentials of 0, −0.19, −0.26, 0, and −0.15 V, respectively. These catalysts effectively suppress the formation of byproducts (N₂O/N₂) and the hydrogen evolution reaction (HER), thereby ensuring high NH₃ selectivity. Our theoretical study confirms that TM@WS₂ catalysts are highly promising for achieving high activity, selectivity, and stability in eNORR, providing valuable insights for future experimental investigations into efficient NH₃ production. Full article