Surface-confined self-reconstruction to sulfate-terminated ultrathin layers on NiMo3S4 toward biomass molecule electro-oxidation

Developing high-performance anode electrocatalysts is desirable in electrocatalytic energy devices powered by sustainable electricity. Compared to water oxidation using Ni-based anodes, electro-oxidation upgrading of biomass molecule with larger size lacks dynamics driving due to increased thickness and decreased electron transfer kinetics of insulating NiOOH amorphous layer (>50 nm) from uncontrollable in-depth reconstruction. Herein, a self-confined surface reconstruction strategy is proposed to construct ∼5 nm-thick NiOOH layers on NiMo3S4 with superior activity and stability for 5-hydroxymethylfurfural oxidation reaction (HMFOR). In-situ high-valence Mo-O coordination and sulfate-terminated anion groups effectively prevent in-depth surface oxidation, leading to the ultra-thin active layers with increased electron transfer kinetics. The surface self-reconstructed NiMo3S4 (NiMo3S4-R) exhibits nearly 100% of HMF conversion, FDCA selectivity and Faradaic efficiency, much better than sulfate-modified NiOOH and pure NiOOH. Moreover, a paired electrolyzer of NiMo3S4-R||NiMo3S4 for HMFOR||HER is also assembled with an ultralow voltage of 1.414 V at 10 mA cm−2.