Accelerated electrochemical-chemical turnover on N-modified Co3O4 with crystalline-amorphous interfaces for efficient glycerol electrooxidation

Urea tailors Co 3 O 4 nanoflakes, Co–N coordination, and interfacial disorder. • Co 3 O 4 /NF-5 reaches 1000 mA cm −2 at 1.39 V with >84.1% formate FE. • CoOOH-mediated electrochemical-chemical turnover governs glycerol oxidation. • A GOR||HER MEA sustains 200 mA cm −2 at 1.9 V for 216 h. • Techno-economic analysis estimates a net profit of $3085.7 per ton of glycerol. Electrochemical glycerol oxidation offers a sustainable pathway for valorizing biodiesel-derived glycerol while lowering the energy demand of hydrogen production. However, Co-based catalysts are often limited by inefficient coupling between the electrochemical generation and chemical consumption of oxidized Co species. Herein, a urea-mediated strategy is developed to simultaneously tailor the morphology, surface electronic structure, and local structural order of Co 3 O 4 electrodes. Urea directs the formation of vertically aligned nanoflakes, introduces Co–N coordination, increases the surface Co 3+ /Co 2+ ratio, and generates defect-rich crystalline-amorphous interfacial regions. The optimized Co 3 O 4 /NF-5 electrode delivers 1000 mA cm −2 at 1.39 ± 0.02 V, maintains a formate Faradaic efficiency above 84.1 ± 1.4% over 1.3–1.8 V, and exhibits only 3.1% activity decay after 5000 cycles. Electrochemical kinetic analysis, in situ Raman spectroscopy, and potential-step measurements reveal efficient electrochemical–chemical turnover mediated predominantly by CoOOH species, with transient Co 4+ -associated species potentially contributing at elevated potentials. Density functional theory calculations further indicate that N incorporation modulates Co 3 d states and strengthens reactant adsorption. An integrated electrolyzer operates continuously for 216 h, demonstrating device-level durability and favorable preliminary techno-economic prospects. These findings establish coupled morphological and electronic regulation as an effective strategy for promoting electrochemical–chemical turnover in glycerol electrooxidation. Download: Download high-res image (154KB) Download: Download full-size image