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The electrochemical CO2 reduction reaction (eCO2RR) to multicarbon products has been widely recognized for Cu‐based catalysts. However, the structural changes in Cu‐based catalysts during the eCO2RR pose challenges to achieving an in‐depth understanding of the structure–activity relationship, thereby limiting catalyst development. Herein, we employ constant‐potential density functional theory calculations to investigate the sintering process of Cu single atoms of Cu−N−C single‐atom catalysts into clusters under eCO2RR conditions. Systematic constant‐potential ab initio molecular dynamics simulations revealed that the leaching of Cu−(CO)x moieties and subsequent agglomeration into clusters can be facilitated by synergistic adsorption of H and eCO2RR intermediates (e.g. CO). Increasing the Cu2+ concentration or the applied potential can efficiently suppress Cu sintering. Both microkinetic simulations and experimental results further confirm that sintered Cu clusters play a crucial role in generating C2 products. These findings provide significant insights into the dynamic evolution of Cu‐based catalysts and the origin of their activity toward C2 products during the eCO2RR. [ABSTRACT FROM AUTHOR]

Proton Exchange Membrane Water Electrolysis (PEMWE) under acidic conditions outperforms alkaline water electrolysis in terms of less resistance loss, higher current density, and higher produced hydrogen purity, which make it more economical in long-term applications. However, the efficiency of PEMWE is severely limited by the slow kinetics of anodic oxygen evolution reaction (OER), poor catalyst stability, and high cost. Therefore, researchers in the past decade have made great efforts to explore cheap, efficient, and stable electrode materials. Among them, the RuO2 electrocatalyst has been proved to be a major promising alternative to Ir-based catalysts and the most promising OER catalyst owing to its excellent electrocatalytic activity and high pH adaptability. In this review, we elaborate two reaction mechanisms of OER (lattice oxygen mechanism and adsorbate evolution mechanism), comprehensively summarize and discuss the recently reported RuO2-based OER electrocatalysts under acidic conditions, and propose many advanced modification strategies to further improve the activity and stability of RuO2-based electrocatalytic OER. Finally, we provide suggestions for overcoming the challenges faced by RuO2 electrocatalysts in practical applications and make prospects for future research. This review provides perspectives and guidance for the rational design of highly active and stable acidic OER electrocatalysts based on PEMWE. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction reaction (CO2RR) over Cu catalysts exhibits enormous potential for efficiently converting CO2 to ethylene (C2H4). However, achieving high C2H4 selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO2RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu‐based material to a pathway that facilitates CO2 reduction to C2H4 products. An excellent Faraday efficiency (FE) of 63.6 % on C2H4 with a current density of 497.2 mA cm−2 in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH4. The in situ X‐ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cuδ+ during the CO2RR. Furthermore, theoretical calculations demonstrate that the Cuδ+/Cu0 interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C2H4 production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO2 reduction to value‐added chemicals. [ABSTRACT FROM AUTHOR]

The grain boundary structure of hexagonal boron nitride is modeled via first principles calculation, based on which, single-atom catalysts are constructed and an excellent overpotential of nitrogen electrocatalytic reduction (NRR) of 0.13 V is obtained. Beyond this new catalyst design strategy, mechanistic studies also provide new evidence on how the grain boundary catalysis works. [Display omitted] • Modeled the grain boundary structure of hexagonal boron nitride. • Screened a series of transition metals that anchored on grain boundary in terms of their NRR catalytic activity. • Demonstrated a spin modification effect at the grain boundary, and explained why this effect can enhance the catalytic performance. Designing high-efficiency electrocatalysts is of great significance to produce ammonia via electroreduction reaction of nitrogen (NRR). To this end, grain boundary catalysis (GBC) has emerged as a promising strategy experimentally. Herein, based on first principles calculations, we modeled the grain boundary (GB) structures of hexagonal boron nitride (h-BN), then 12 transition metal atoms (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Y, Zr, Mo, Ru, and Rh) were anchored on the GB structures to construct single-atom catalysts, the most ideal overpotential of NRR is as low as 0.13 V for Mo adatoms on GB. Additionally, more sophisticated situations in regard to h-BN GB were considered, meanwhile electronic structure analysis was also conducted. We found that, the configuration and density of GB can hardly influence the catalytic activity at GB, while the coordinated B bonded with Mo strongly modified the spin states and the bonding strengths within certain intermediates, leading to this excellent NRR catalytic activity. This work not only provides a new strategy for the development of highly efficient and stable NRR electrocatalysts, but also enhances the understanding on the origin of GBC. [ABSTRACT FROM AUTHOR]

A theoretical study on modulation of local coordination environment of main group metals in M−N−C catalysts toward oxygen reduction reaction (ORR) has been conducted. DFT results show that MgN 2 O 2 is at the peak of the volcano, which is ascribed to more shifts of p-band position of Mg away from the Fermi energy level and the lower O highest occupied energy level. [Display omitted] • MgN 2 O 2 is a promising candidate for oxygen reduction reaction; • The lower ORR overpotential on MgN 2 O 2 is ascribed to more shifts of p-band position of Mg and the lower O highest occupied energy level of OH*; • There is a linear relationship between adsorption free energies of OH* and O highest occupied energy levels of OH*. For the 4e– oxygen reduction reaction (ORR) on main group metal-nitrogen-carbon catalysts, the effect of the local coordination environment of main group metals on ORR has rarely been reported. By performing density functional theory (DFT) calculations, we screen 18 MN 4–x O x (x = 0–2, M = Mg, Ca, Sr, Al, Ga, In) candidates with different metal coordination environments and construct volcano curve between the adsorption free energy of OH* (ΔG OH*) and ORR overpotential, yielding MgN 2 O 2 at the peak of the volcano with the overpotential as low as 0.55 V. The lower ORR overpotential on Mg coordinated with 2 N and 2 O atoms than other coordination environments is well explained by the decreased ΔG OH* because of more shifts of p-band position of Mg away from the Fermi energy level as well as the lower O highest occupied energy level when the number of the coordinated O atoms increases. Our DFT work provides theoretical guidance for engineering ORR performance of main group metal-nitrogen-carbon catalysts by modulating coordination environments. [ABSTRACT FROM AUTHOR]