One-Step Hydrothermal Synthesis of Phase-Engineered MoS₂/MoO₃ Electrocatalysts for Hydrogen Evolution Reaction

Abstract

The development of suitable approaches for the synthesis of ultrathin transition-metal dichalcogenide (TMD) catalysts is required to engineer phases, intercoupling between different phases, in-plane defects, and edges and hence maximize their catalytic performance for hydrogen production. In this work, we report a simple one-step hydrothermal approach for the synthesis of<br/>a three-dimensional (3D) network of self-assembled metallic MoS2/MoO3 nanosheets, using α-MoO3 and thiourea (TU) as the Mo<br/>and S precursors, respectively. A systematic structural/property relationship study, while varying the precursors’ molar concentration<br/>ratios (TU/MoO3) and reaction temperatures (TR), revealed a kinetically controlled regime, in hydrothermal synthesis, that enabled<br/>the formation of ultrathin branched MoS2/MoO3 nanosheets with the highest metallic content of ∼47 % in a reproducible manner.<br/>Importantly, the work established that in addition to the rich metallic MoS2 phase (1T), the electronically coupled interfaces<br/>between MoO3 and MoS2 nanodomains, profusion of active sites, and tuned electrical conductivity significantly contributed to<br/>hydrogen evolution reaction (HER)-catalytic activity, affording a low overpotential of 210 mV (with respect to the reversible<br/>hydrogen electrode) at a current density of 10 mA/cm2<br/>, a small Tafel slope of ∼50 mV/dec, and high stability. Overall, this work<br/>demonstrated a controllable one-step hydrothermal method for the rational design and synthesis of a 3D network of MoS2/MoO3<br/>nanosheets with high 1T-MoS2 metallic yield, simultaneous incorporation of MoO3/MoS2 heterointerfaces, sulfur vacancies, and<br/>tuned electrical conductivity, which are highly beneficial for clean energy conversion applications that can potentially be expanded to<br/>other two-dimensional TMD materials.

Topics & Concepts