Ge Yao's research while affiliated with Nanjing University and other places

Transition metal macrocyclic complexes are appealing catalysts for electrochemical oxygen reduction reaction (ORR). Here, we perform first-principles calculations to gain a comprehensive understanding on the structure-property relationship of the metal macrocyclic complex systems. Various modifications of the complexes are considered, including centered metal, axial ligand, coordination atom, substituent, and macrocycles. Based on simulation, introduction of appropriate apical ligand can improve the performance of all the three metals, whereas replacement of nitrogen with oxygen or carbon as the coordination atoms may enhance the Ni-centered systems. The antiaromatic ring stabilizes the ∗OOH intermediate, whereas the macrocycle with reduced electron density inhibits the binding with oxygen. By regulating the coordination environment, the overpotential can be significantly reduced. This work may assist the rational design of ORR catalysts and is of great significance for the future development of oxygen reduction catalysts.

Amorphous carbon (aC) is widely used as the adsorbent in the purification of industrial gas. Introducing nitrogen dopant can regulate the morphology and improve the adsorption capacity of specific species. Due to the amorphous structure, it is difficult to understand the relationship between structural features and adsorption performance through atom‐based simulation. Here, a series of nitrogen‐doped amorphous carbon (N‐aC) models is built through reverse Monte Carlo method. The uptakes of three common gases, i.e., CO2, CH4, and N2 are estimated in each constructed framework by using grand canonical Monte Carlo (GCMC). Deep neural network is trained based on the simulated adsorption capacity with nitrogen content, surface area, pore size, atomic charge, and other factors. Through the data‐driven approaches, the adsorption capacity and the selectivity of three gases are predicted. The simulation in this study shows that the nitrogen content has less influence on the capacity and selectivity than the structural parameters, while nitrogen doping may improve CO2 loading and separation selectivity in the nanopores with pore size close to gas molecules. This work is helpful in constructing amorphous carbon structures for further simulation and understanding the influence of various features on gas separation.

Exploring electrocatalysts with high activity, selectivity, and stability is essential for the development of applicable electrocatalytic ammonia synthesis technology. By performing density functional theory calculations, we systematically investigated the potential of a series of transition-metal-doped Au-based single-atom alloys (SAAs) as promising electrocatalysts for nitrogen reduction reaction (NRR). The overall process for the Au-based electrocatalyst suffers from the limiting potential arising from the first hydrogenation step of the reduction of *N2 to *NNH. However, SAAs showed to be favorable toward lowering free energy barriers by increasing the binding strength of N2. According to simulation results, three descriptors were proposed to describe the first hydrogenation step ΔG(*N2 → *NNH): ΔG(*NNH), d-band center, and d/√Em. Eight doped elements (Ti, V, Nb, Ru, Ta, Os, W, and Mo) were initially screened out with a limiting potential ranging from -0.75 to -0.30 V. Particularly, Mo- and W-doped systems possess the best activity with a limiting potential of -0.30 V each. Then, the intrinsic relationship between the structure and potential performance was analyzed using machine learning. The selectivity, feasibility, and stability of these candidates were also evaluated, confirming that SAA containing Mo, Ru, Ta, and W could be outstanding NRR electrocatalysts. This work not only broadens our understanding of SAA application in electrocatalysis, but also leads to the discovery of novel NRR electrocatalysts.

Solar-driven reduction of CO2 into multi-carbon products plays a vital role in renewing CO2 utilization, while the key lies on screening efficient catalysts that possess moderate CO intermediate binding energy and eventually facilitate further C–C coupling to C2+ products. Herein, we proposed a synergistic coupling catalyst by anchoring the heteroatom B–Co dimer into porous C2N (B–Co@C2N) for photocatalytic CO2 reduction into ethane via applying first-principles calculations. The formation of the B–Co dimer can effectively modulate the Co-3d orbital toward lower energy levels, which weakens CO adsorption strength compared with Co–Co@C2N and leads to a low C–C coupling energy barrier of ∼0.61 eV. The undesirable hydrogen evolution reaction is drastically suppressed due to the strong adsorption of the *CO2/*COOH intermediate with positive limiting potential difference of UL(CO2)–UL(H2). More importantly, the light absorbance of B–Co@C2N is significantly enhanced in the visible and infrared light range compared with that of pure C2N. The high binding energy combined with the AIMD simulations ensured structural stability and feasibility for future experimental synthesis. Our proposed synergy concept of single metal atom and nonmetal atom hybrids is expected to open a new avenue toward photocatalytic CO2 reduction into multi-carbon products under visible light.

Using density functional theory (DFT) calculations, we explored the potential of defective MoS2 sheets decorated with a series of single transition metal (TM) atoms as electrocatalysts for N2 reduction reaction (NRR). The computed reaction free energy profiles reveal that the introduction of embedded single TM atoms significantly reduces the difficulty to break the N≡N triple bond, and thus facilitates the activation of inert nitrogen. Onset potential close to -0.6 V could be achieved by anchoring various transition metals, such as Sc, Ti, Cu, Hf, Pt, and Zr, and the formation of the second ammonia molecule limits the overall process. Ti-decorated nanosheet possesses the lowest free energy change of -0.63 eV for the potential determining step. To better predict the catalysis performance, we introduced a descriptor, φ, which is the product of the number of valence electron multiplying by the electronegativity of the decorated TM. It shows good linear relationship between the d-band center and the binding energy of nitrogen, except for those metals with less than half filled d-band. Although the metals in Group IIIB and IVB have strong adsorption interactions with N atom, the Gibbs free energy changes for desorption of the second ammonia are unexpectedly low. The selectivity of these systems towards nitrogen reduction reaction (NRR) are also significantly improved. Therefore, those defective MoS2 decorated with Sc, Ti, Zr and Hf are suggested as promising electrocatalysts for NRR, for their both high efficiency and selectivity.

The MXene‐supported single transition metal systems have been reported as promising electrocatalysts for hydrogen evolution reaction (HER) and carbon dioxide reduction reaction. Herein, the potential performance of MXene‐based catalysts was explored on nitrogen reduction reaction (NRR). Density functional theory computations are carried out to screen a series of transition metal atoms confined in a vacancy of MXene nanosheet (Mo2TiC2O2). The results reveal that the Zr, Mo, Hf, Ta, W, Re, and Os supported on defective Mo2TiC2O2 layer can significantly promote the NRR process. Among them, Zr‐doped single atom catalyst (Mo2TiC2O2‐ZrSA) possesses the lowest barrier (0.15 eV) of the potential‐determining step, as well as high selectivity over HER competition. To the best of knowledge, 0.15 eV is the lowest barrier of potential‐determining step that has been reported for NRR so far. Besides, the formation energy of Mo2TiC2O2‐ZrSA is much more negative than that of the synthesized Mo2TiC2O2‐PtSA catalyst, suggesting that the experimental preparation of Mo2TiC2O2‐ZrSA is feasible. This work thus predicts an efficient electrocatalyst for the reduction of N2 to NH3 at ambient conditions.

In the present study, a highly efficient strategy is reported using open framework platforms with abundant chelating ligands to fabricate a series of stable metal single‐atom catalysts (SACs). Here, the metal ions are initially anchored onto the active bipyridine sites through postsynthetic modification, followed by pyrolysis and acid leaching. The resulting single metal atoms are uniformly distributed on a nitrogen‐doped carbon (N‐C) matrix. Interestingly, each metal atom is found to be coordinated with five N atoms, in contrast to the average coordination number of four as previously reported. The as‐prepared Fe SAC/N‐C catalyst exhibits excellent oxygen reduction reaction (ORR) activity (with a half‐wave potential of 0.89 V), outstanding stability, and good methanol tolerance. The density functional calculations reveal that the coordinated pyridine can favorably modulate the interaction strength of oxygen on the Fe ion and thus improve the ORR activity. More importantly, it is demonstrated that this strategy can be successfully extended to the preparation of other transition metal SACs, simply by altering the metal precursors used in the metalation step. A new and generic strategy using open porous frameworks with chelating ligands is proposed to fabricate metal single‐atom catalysts (SACs). As a proof of concept, a series of metal SACs (metal = Fe, Co, Ni, and Cu) are constructed. The as‐prepared Fe SAC exhibits excellent oxygen reduction reaction (ORR) activity.