Anti-Sintering Ni-W Catalytic Layer on Reductive Tungsten Carbides for Superior High-Temperature CO₂ Reduction.

Abstract

The reverse water-gas shift (RWGS) reaction stands out as a promising approach for selectively converting CO₂ into CO, which can then be upgraded into high-value-added products. While designing high selectivity and stability catalysts for RWGS reaction remains a significant challenge. In this study, an efficient and ultra-stable Ni-W catalytic layer on reductive WC (Ni_AWC) is designed as an anti-sintering catalyst for superior high-temperature RWGS reaction. Benefiting from the unique structures, the Ni_AWC catalyst exhibits exceptionally high performances with a CO production rate of 1.84 mol_CO g_Ni ^-1 h^-1 and over 95% CO selectivity, maintaining stability for 120 h at 500 °C. Even after 300 h of continuous testing at 600 °C and five aging cycles at 800 °C, the activity loss is only 0.34% and 0.83%, respectively. Unlike the conventional mechanism in RWGS reaction, it is demonstrated that the Ni-W limited coordination can stabilize the Ni sites and allow a pre-oxidation of Ni^δ+ by CO, which produces an O* electronic reservoir and hinders the charge transfer from Ni to W-O, thereby avoiding the dissolution of Ni atoms. The design of new, efficient, and selective catalysts through metal-substrate synergistic effects is suggested to offer a promising path to engineering superior thermal catalysts.