Highly active and stable bifunctional electrocatalysts for overall water splitting are important for clean and renewable energy technologies. The development of energy-saving electrocatalysts for hydrogen evolution reaction (HER) by replacing the sluggish oxygen evolution reaction (OER) with a thermodynamically favorable electrochemical oxidation (ECO) reaction has attracted increasing attention. In this study, a self-supported, hierarchical, porous, nitrogen-doped carbon (NC)@CuCo 2 N x /carbon fiber (CF) is fabricated and used as an efficient bifunctional electrocatalyst for both HER and OER in alkaline solutions with excellent activity and stability. Moreover, a two-electrode electrolyzer is assembled using the NC@CuCo 2 N x /CF as an electrocatalyst at both cathode and anode electrodes for H 2 production and selective ECO of benzyl alcohol with high conversion and selectivity. The excellent electrocatalytic activity is proposed to be mainly due to the hierarchical architecture beneficial for exposing more catalytic active sites, enhancing mass transport. Density functional theoretical calculations reveal that the adsorption energies of key species can be modulated due to the synergistic effect between CoN and CuN. This work provides a reference for the development of high-performance bifunctional electrocatalysts for simultaneous production of H 2 and high-value-added fine chemicals.

Considerable research efforts have been devoted to the lithium−sulfur battery due to its advantages such as high theoretical capacity, high energy density, and low cost. However, the shuttle effect and the irreversible deposition of Li 2 S result in severe capacity decay and low Coulombic efficiency. Herein, we discovered that the transition metal phosphides cannot only trap the soluble polysulfides but also effectively catalyze the decomposition of Li 2 S to improve the utilization of active materials. Compared with the cathodes without transition metal phosphides, the cathodes based on Ni 2 P, Co 2 P, and Fe 2 P all exhibit higher reversible capacity and improved cycling performance. The Ni 2 P-added electrode delivers capacities of 1165, 1024, 912, 870, and 812 mAh g −1 at 0.1, 0.2, 0.5, 1.0, and 2.0 C, respectively, and high capacity retention of 96% after 300 cycles at 0.2 C. Even with a high sulfur mass loading of 3.4 mg cm −2 , the capacity retention remains 90.3% after 400 cycles at 0.5 C. Both density functional theory calculations and electrochemical tests reveal that the transition metal phosphides show higher adsorption energies and lower dissociation energies of Li 2 S than those of carbon materials.

Stabilizing single-atom metal catalysts with carbon materials and utilizing their synergistic effect remains challenging due to weak interactions between carbon-based supports and metals. Density functional theory (DFT) calculations indicate that a single Ru atom was supported on a wide range of natural nanoporous carbon materials, including C 2 N, triazine-C 3 N 4 (T-C 3 N 4 ), and γ -graphene. These carbon materials belong to a new generation of highly efficient electrocatalysts for the N 2 reduction reaction (NRR) and are named Ru 1 @C 2 N, Ru 1 @T-C 3 N 4 , and Ru 1 @γ -graphyne, respectively. Ab initio molecular dynamic (AIMD) simulations show that a single Ru atom can be stably anchored in the nanopores of these carbon materials with strong cohesive energy. Compared with parallel adsorption configuration, the vertical adsorption configuration of N 2 exhibits higher adsorption energy. The calculated Gibbs free energy reveals N 2 reduction on the three catalysts via associative mechanisms. Despite the similar limiting potentials (−0.96, −0.94, and −0.98 V on Ru 1 @C 2 N, Ru 1 @T-C 3 N 4 , and Ru 1 @γ -graphynes, respectively), the limiting step differs, indicating the significant effects of carbon material substrates on electrochemical NRR. However, the competitive and efficient hydrogen evolution reaction (HER) changes the potential determining step and increases the overpotential for the electrochemical nitrogen reduction (NRR). This study provides insights for experimental synthesis of electrocatalysts for N 2 reduction.

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Selective electrocatalytic oxidation (ECO) of benzyl alcohol to benzoic acid or benzaldehyde over 1.0 h-Ni(OH)2 with excellent conversion, selectivity, and stability in a two compartment H cell is presented.