Hierarchical MoS2@NiFeCo-Mo(doped)-LDH Heterostructures as Efficient Alkaline Water Splitting (Photo)Electrocatalysts

Designing cost-effective electrocatalysts with fast reaction kinetics and high stability is an outstanding challenge that needs to be resolved to enable green hydrogen generation through overall water splitting (OWS). Layered double hydroxide (LDH) heterostructure materials are promising candidates to catalyze both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), the two half-cell reactions of OWS. This work develops a facile hydrothermal route to synthesize hierarchical het- erostructure MoS2@NiFeCo-Mo(doped)-LDH electrocatalysts, which exhibit extremely good OER and HER performance as witnessed by their low overpotentials of 178 mV and 64 mV, respectively, at a current density of 10 mA/cm2 under light assistance. The MoS2@NiFeCo-Mo(doped)-LDH‖MoS2@NiFeCo-LDH OWS cell demonstrates a low cell voltage of 1.46 V at 10 mA/cm2 during light-assisted water electrolysis. The experimental and computational results demonstrate that doping of high-valence Mo atoms within and the deposition of MoS2 quantum dots on the LDH matrix improves the electrocatalytic activity by 1) enhancing electron transfer, 2) making the elec- trocatalyst metallic, 3) increasing the number of active sites, 4) lowering the ther- modynamic overpotential, and 5) changing the OER mechanism. Overall, the facile synthesis method enables the design of highly active MoS2@NiFeCo-Mo(doped)-LDH heterostructure electrocatalysts.