Tuning the crystal facets of MoP2 in a phosphide–nitride heterostructure via interface engineering for energy-efficient ethanol oxidation-coupled H2 production

Abstract

Efforts to enhance the electrocatalytic activities of transition-metal-based nanocatalyst systems are important to improve their viability and commercial exploitation. In this work, the crystal facets of MoP₂ in an MoP₂/MoN heterojunction are tailored using a controlled hydrothermal procedure. The active facets of MoP₂ (131) and MoN (200) phases in this heterostructure possess similar lattice spacing and display effective ethanol oxidation reaction (EOR)-promoted H₂ production ability under alkaline conditions. The j_EOR and j_HER values of 100 mA cm⁻² are realized at 1.34 and −0.18 V_RHE, respectively, in a 1.0 M KOH + 1.0 M EtOH solution, supporting the activity. The j value of 100 mA cm⁻² is realized at a reasonable potential value of 1.62 V in a 1.0 M alkaline solution in the two-electrode mode. Importantly, the EtOH-to-acetate conversion is realized at a relatively high yield of 75.78% at 1.60 V, supporting the viability of the process. The post-electrolysis characterization revealed retention of major structural features, supporting the durability of the heterostructure and the viability of further practical implications. The study revealed that tuning of the crystal facets offers an effective means to fine-tune the electrocatalytic behaviour and improve the energy efficiency of the overall electrocatalytic operation.