Regulating the Electronic Structure of CoP Nanosheets by O Incorporation for High‐Efficiency Electrochemical Overall Water Splitting

Abstract

The exploration of earth‐abundant and high‐efficiency bifunctional electrocatalysts for overall water splitting is of vital importance for the future of the hydrogen economy. Regulation of electronic structure through heteroatom doping represents one of the most powerful strategies to boost the electrocatalytic performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, a rational design of O‐incorporated CoP (denoted as O‐CoP) nanosheets, which synergistically integrate the favorable thermodynamics through modification of electronic structures with accelerated kinetics through nanostructuring, is reported. Experimental results and density functional theory simulations manifest that the appropriate O incorporation into CoP can dramatically modulate the electronic structure of CoP and alter the adsorption free energies of reaction intermediates, thus promoting the HER and OER activities. Specifically, the optimized O‐CoP nanosheets exhibit efficient bifunctional performance in alkaline electrolyte, requiring overpotentials of 98 and 310 mV to deliver a current density of 10 mA cm−2 for HER and OER, respectively. When served as bifunctional electrocatalysts for overall water splitting, a low cell voltage of 1.60 V is needed for achieving a current density of 10 mA cm−2. This proposed anion‐doping strategy will bring new inspiration to boost the electrocatalytic performance of transition metal–based electrocatalysts for energy conversion applications.

Large‐Size, Porous, Ultrathin NiCoP Nanosheets for Efficient Electro/Photocatalytic Water Splitting

“…[ 29 ] Additionally, 2D nanomaterials, for example, nanosheets, characteristics of large surface area and rich exposed edge active sites as well as large contact area with the electrolyte for fast interfacial charge transport, are widely designed and prepared for promising electrocatalysts. [ 30–36 ] The ultrathin 2D nanomaterials can achieve over 40 times higher electrocatalytic activity than its bulk counterpart. [ 37 ] Xie's group has demonstrated that the electrocatalytic performance is largely dependent upon the thickness of 2D nanomaterials by enhancing electrical conductivity, varying exposure to coordinately unsaturated surface atoms and shortening the ion diffusion paths.…”

Hollow cobalt-nickel phosphide nanocages for efficient electrochemical overall water splitting

“…However, because of the sluggish reaction kinetics and non-negligible overpotential (η) for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) during water electrolysis [5][6][7][8], the large-scale H 2 preparation is seriously restricted, which has driven the exploration of high-efficiency electrocatalysts. Nowdays, the most widely used electrocatalysts for HER and OER are noble metals and their oxides, such as platium (Pt) [9,10], iridium (Ir) [11,12], iridium dioxide (IrO 2 ) [13,14] and ruthenium (Ru) [15][16][17]. Unfortunately, the scarcity and high-costs hinder their industrial applications.…”

Coupling NiCo Alloy and CeO2 to Enhance Electrocatalytic Hydrogen Evolution in Alkaline Solution

“…The performance for the NiCo-CeO 2 ||NiCo(OH) x -CeO 2 electrolyzer also outperforms most recently reported electrolyzers based on non-noble bifunctional electrocatalysts (Figure 5e; Table S4, Supporting Information). [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] The excellent overall water splitting activity of the NiCo-CeO 2 ||NiCo(OH) x -CeO 2 electrolyzer is not only attributed to the high intrinsic catalytic activities of NiCo-CeO 2 / GP and NiCo(OH) x -CeO 2 /GP, but also to the self-supported electrode structure. Due to the in situ growth of active species on conductive substrate, the interface resistances of the self-supported NiCo-CeO 2 /GP and NiCo(OH) x -CeO 2 /GP electrodes are greatly lower than those of the Pt/C(20%)/GP and RuO 2 /GP electrodes by physically coating (Figure S25, Supporting Information), which are conducive to the rapid electron transfer.…”

“…The performance for the NiCo–CeO 2 ||NiCo(OH) x –CeO 2 electrolyzer also outperforms most recently reported electrolyzers based on non‐noble bifunctional electrocatalysts (Figure 5e; Table S4, Supporting Information). [ 45–59 ]…”