Heterogeneous Interface Engineering of CoMoP/C₃N₄/N-Doped Carbon to Boost Overall Water Splitting

Abstract

The design of efficient and cost-effective bifunctional catalysts, which are capable of driving both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), is of paramount importance for advancing overall water splitting. Here, we developed an innovative heterogeneous interface engineering strategy to boost the electrocatalytic performance of overall water splitting. This approach involves the synergistic integration of ultra-fine CoMoP nanocrystals coupled with three-dimensional (3D) porous C₃N₄/N-doped carbon (NC) architectures, constructing a distinctive CoMoP/C₃N₄/NC heterogeneous interface. The CoMoP/C₃N₄/NC exhibits distinguished overall water splitting performance. To drive the overall water splitting current of 10 mA cm⁻², the CoMoP/C₃N₄/NC||CoMoP/C₃N₄/NC electrolysis cell only needs an ultralow cell voltage of 1.496 V. The electronic properties and localized coordination environments characterizations, and density functional theory (DFT) calculations elucidate that the improved catalytic activities of CoMoP/C₃N₄/NC are primarily attributed to the synergistic interfacial coupling between CoMoP/C₃N₄/NC heterogeneous interface. A novel multi-site synergistic catalytic mechanism was revealed by the DFT calculations, in which the optimum H* adsorption site on CoMoP/C₃N₄/NC for HER is on the cobalt atoms in CoMoP with the ultralow Gibbs free energy of hydrogen bonding (ΔG_H*) of 0.018 eV, while for the OER, the optimum intermediates adsorption site of the CoMoP/C₃N₄/NC is on the carbon atoms in C₃N₄/NC. Besides, the intricately engineered 3D hierarchical porous framework of the CoMoP/C₃N₄/NC can facilitate the ion and electron transport and improve mass transfer, which gives rise to enhanced water splitting performance.

Keywords

bifunctional catalyst / bimetallic phosphide / heterogeneous interface engineering / hydrogen evolution reaction / overall water splitting / oxygen evolution reaction

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