2D Titanate Nanosheet–Supported NiMoO x Core@shell Nanospikes for Overall Electrocatalytic Water-Splitting Reactions

Carbon-based materials that act as supports to design electrocatalysts have been actively pursued for fuel cells and overall water-splitting (OWS) applications. However, carbon-based supports face serious carbon corrosion at high positive potentials, affecting catalyst activity and stability and hindering practical applicability. Herein, carbon-free transition metal-oxide–based 2D titanate nanosheet support has been proposed, demonstrating the applicability of titanate nanosheets as an alternative support for designing electrocatalysts. A new chemical route to produce large 2D nanosheets of titanate via exfoliation has been discovered. Colloidal 2D titanate nanosheet support allows the growth of active nickel molybdenum oxide (NiMoO x ) forming Titanate@NiMoO x core–shell materials. Fine heat treatment at different temperatures facilitates in situ formation of MoO x in NiMoO x layers on 2D titanate boosting catalytic activity. An increase in heat treatment facilitates an increase in the semiconductivity of the titanate phase and a simultaneous decay of the active MoO x component, resulting in poor activity. The optimal catalyst Titanate@NiMoO x _200 required an overpotential of 0.54 and 1.19 VRHE for the HER and the OER and an overall cell voltage of 1.75 V to deliver a current density of 10 mA cm–2 with spectacular stability for up to 24 h in KOH media. Spectroscopic and microscopy analyses prove the efficient electronic interaction between MoO x and NiMoO x in the hybrid components. Density functional theory and experimental work suggest that the MoO x /NiMoO x hybrid shows higher water adsorption energy and excellent water-splitting performance. This work sheds light on the feasibility and practical application of titanate support for the rational design of diverse electrocatalysts from noble to non-noble metal-based electrocatalysts for a range of electrochemical applications.