Heterointerface Engineering of Cerium Fluoride Confined Molybdenum Nitride for Overall Water Splitting

Abstract

The pursuit of highly efficient, pollution-free hydrogen generation using bifunctional electrocatalyst consist of rare-earth metal and non-noble metal is of paramount important. However, it is formidable task still in Mo-derived catalysts due to agglomeration with strong Mo-H binding. Herein, bifunctional CeF3@Mo2N heterostructure has been designed which exhibits exciting HER and OER activity with low overpotential of 195 and 311 mV and corresponding Tafel slope of 101 and 107 mV dec−1, respectively. Remarkable synergistic effect of CeF3 with Mo2N increased the catalytically active surface area to expose abundant active sites, porosity and intimate contact between CeF3@Mo2N and NF to regulate the electronic redistribution around Mo sites for remarkable activity. Mechanistic investigation inferring built-in electric field (BIEF) at Schottky interface narrowed the band gap of CeF3@Mo2N to improve charge transport during electrolysis. The heterointerface downshift the d-band center of active Mo center which weakened Mo-H strength to control the adsorption ability of intermediates on surface reaction sites for higher performance. The enhanced *OH adsorption on CeF3@Mo2N was further verified by Laviron analysis. The kinetics of CeF3@Mo2N electrolysis was examined via impedance analysis and demanding very small activation energy to complete the reaction after CeF3-coupling, as supported by Arrhenius plot. The higher rate constant extracted from Trumpet curve for CeF3@Mo2N inferring rapid formation of O2 bubbles. CeF3@Mo2N exhibits 1.48 V@10 mA cm−2 for (CH2OH)2 oxidation reaction (EGOR) with high stability and high Faradaic efficiency (FE), surpassed high-end electrocatalysts. Alkaline-/solar-driven electrolyzer of CeF3@Mo2N(+,-) required 1.59 V indicating promising prospects for practical applications.