Electrocatalytic Selective Glycerol Oxidation toward Biodiesel Wastewater Valorization by Pd–Au Nanoalloy Catalysts

Crude glycerol is the primary byproduct in the biodiesel production process, representing an emerging waste stream that can be used to manufacture value-added products. Herein, a Pd 8 Au 1 nanoalloy catalyst was developed for electrocatalytic glycerol oxidation, achieving a remarkably high current density exceeding 0.5 A cm –2 at a low potential of 0.95 V vs RHE. The glycerol conversion rate reaches 1.42 mmol cm –2 h –1, which is 8.88 and 5.92 times higher than the rates of monometallic Au and Pd catalysts, respectively. This system exhibits over 85% selectivity toward high-value C 3 products (glyceric acid and lactic acid). Mechanistic investigations reveal that Au incorporation downshifts the d-band center of Pd, which reduces the activation barrier of the rate-determining step and accelerates the desorption of intermediates, thereby promoting the formation of target C 3 species. The generated products can serve as both precursors for fine chemicals and high-quality carbon sources that enhance microbial denitrification. Techno-economic analysis indicates that the electrochemical valorization process could yield a profit exceeding 476 USD per ton of waste glycerol. This study establishes a novel paradigm for efficiently recycling and valorizing waste biomass through electrocatalytic conversion.