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Nitrogen-doped graphene supported single metal atoms are expected to achieve high nitrogen reduction reaction (NRR) performance via the electroreduction process. Based on density functional theory (DFT) calculations, the application of three pyrrolic-N doped graphene (pyrrolic-N3–G) supported V1, Cr1, Mn1, Fe1, Nb1, Mo1, W1 and Re1 as electrocatalysts for NRR is evaluated from stability, limiting potential and ammonia selectivity points of view. Mo1(W1, Re1)/pyrrolic-N3–G are predicted to be potential candidates for NRR with high stability, less negative limiting potential (−0.49, −0.33 and −0.51 V) and high ammonia selectivity, which indicates that the catalytic performances are improved from both activity and selectivity aspects compared to the corresponding pyridine-N3–G supported ones. The identified descriptors indicate that the accumulated charges on metal atoms and the adsorbed hydrogen atoms have considerable impacts on limiting potential and selectivity, respectively. It is also suggested that the NRR activity can be tuned by changing the coordination environment and the response of changing coordination environments differs according to the type of transition metals.

The chemical coupling interaction has been explored extensively to boost heterogeneous catalysis, but the insight into how chemical coupling interaction works on CO2 electroreduction remains unclear. Herein we demonstrate how the chemical coupling interaction between porous In2O3 nanobelts and reduced graphene oxide (rGO) could substantially improve the electrocatalytic activity toward CO2 electroreduction. Such an In2O3-rGO hybrid catalyst showed 1.4-fold and 3.6-fold enhancements in Faradaic efficiency and specific current density for the formation of formate at -1.2 V versus reversible hydrogen electrode relative to the catalyst prepared by physically loading of In2O3 nanobelts onto rGO, respectively. The density functional theory calculations and electrochemical analysis together revealed that the chemical coupling interaction boosted CO2 electroreduction activity by improving electrical conductivity and stabilizing key intermediate HCOO-*. The present work not only deepens an understanding of chemical coupling effect but also provides an effective lever to optimize the catalytic performance toward CO2 electroreduction.

The electrochemical reduction of nitrogen to ammonia is a promising way to produce ammonia at mild condition. The design and preparation of an efficient catalyst with high ammonia selectivity is critical for the real applications. In this work, a series of transition metal (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, and Cd) atoms supported by gt-C3N4 (TM/gt-C3N4) are investigated as electrocatalysts for the nitrogen reduction reaction (NRR) based on density functional calculations. It is found that Mo/gt-C3N4 with a limiting potential of -0.82 V is the best catalyst for standing-on adsorbed N2 cases. While for lying-on adsorbed N2 cases, V/gt-C3N4 with a limiting potential of -0.79 V is better than other materials. It is believed that this work provides several promising candidates for the non-noble metal electrocatalysts for NRR at mild condition.

As diversified reaction paths exist over practical catalysts towards CO2 hydrogenation, it is highly desiderated to precisely control the reaction path for developing efficient catalysts. Herein, we report that the ensemble of Pt single atoms coordinated with oxygen atoms in MIL-101 (Pt1@MIL) induces distinct reaction path to improve selective hydrogenation of CO2 into methanol. Pt1@MIL achieves the turnover frequency number of 117 h−1 in DMF under 32 bar at 150 °C, which is 5.6 times that of Ptn@MIL. Moreover, the selectivity for methanol is 90.3% over Pt1@MIL, much higher than that (13.3%) over Ptn@MIL with CO as the major product. According to mechanistic studies, CO2 is hydrogenated into HCOO* as the intermediate for Pt1@MIL, whereas COOH* serves as the intermediate for Ptn@MIL. The unique reaction path over Pt1@MIL not only lowers the activation energy for the enhanced catalytic activity, but also contributes to the high selectivity for methanol. Controlling the reaction path is instrumental for developing efficient catalysts for CO2 hydrogenation. Here, the authors report that the ensemble of Pt single atoms coordinated with oxygen atoms in MIL-101 induces distinct reaction path to improve selective hydrogenation of CO2 into methanol relative to nanocrystal counterparts.