Hierarchically Porous Carbonized Wood Decorated with MoNi₄‐Embedded MoO₂ Nanosheets: An Efficient Electrocatalyst for Water Splitting

Abstract Development of low‐cost electrocatalysts for water splitting is crucial to economical hydrogen production. Here, a highly efficient electrocatalyst composed of MoNi 4 ‐embedded amorphous MoO 2 nanosheets grown on less‐tortuosity hierarchically porous carbonized wood (MoNi 4 /MoO 2 @CW) is reported. The generation of abundant MoNi 4 /MoO 2 heterointerfaces and defects‐rich MoO 2 significantly promote the adsorption and activation of reactant molecules on the MoNi 4 /MoO 2 @CW. The obtained MoNi 4 /MoO 2 @CW catalyst exhibits ultralow overpotentials of 22 and 205 mV for hydrogen evolution reaction and oxygen evolution reaction at a current density of 10 mA cm −2 , respectively. The catalyst can be used for dual‐function electrodes and assembling two‐electrode electrolyzer illustrates 10 mA cm −2 at 1.47 V and superior durability over 24 h for overall water electrolysis. Moreover, it also possesses a high mass activity of 142 Ag −1 MoNi 4 at 200 mV, surpassing the Pt/C catalyst (132 Ag −1 ). The outstanding performance of the MoNi 4 /MoO 2 @CW is attributed to the decrease in energy barrier for water dissociation, optimal adsorption/desorption of H/O‐intermediates, and fast mass transport through the porous structure, as confirmed by experimental results and density functional theory‐based calculations. The MoNi 4 /MoO 2 @CW electrocatalyst has excellent potential for practical water splitting.