Ni-Induced Low-Valence Tungsten Oxide for Highly Selective and Stable Glycerol Electro-Oxidation to Formic Acid.

Abstract

Electrocatalytic upgrading of renewable biomass-derived glycerol represents a sustainable method to produce value-added chemicals, but the complex reaction network of key intermediates during the glycerol oxidation poses challenges to product selectivity. Herein, we report a nickel-doped tungsten oxide catalyst grown on nickel foam (Ni-WOx/NF) for the highly selective electrooxidation of glycerol to formic acid (FA). This optimized catalyst achieves an FA Faraday efficiency (FE) of 95.1% and operates stably for over 18 h, outperforming conventional non-precious metal catalysts. Mechanistic understanding revealed that nickel doping effectively modulates the valence states of tungsten, increasing the proportion of low-valent W4+ species. This promotes the desorption of FA from the catalytic interface, thereby inhibiting its over-oxidation and enhancing selectivity. Taking a step forward, an integrated electrocatalytic system coupling the anodic glycerol oxidation reaction (GOR) with the cathodic nitrate reduction reaction (NO3-RR) is constructed. This system enables the simultaneous coproduction of FA and ammonia (NH3), achieving a high FE for FA of 96.9% along with sustained stability over 12 h, demonstrating significant potential for practical applications. This work demonstrates a sustainable catalytic system for selective glycerol oxidation by precisely regulating the reaction pathways of key intermediates.