Harnessing mechanical energy for biomass valorization: A piezocatalytic biorefinery approach for anaerobic conversion of HMF to DFF and hydrogen via ball-milling activation

This study presents a novel strategy of piezocatalysis driven by ball milling (BM) for the anaerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to high-value 2,5-diformylfuran (DFF) with simultaneous hydrogen (H₂) production. A rationally designed Schottky heterojunction (CS/MB) composed of 1D CdS nanorods (CS) and 2D MoB MBene nanosheets (MB) is synthesized, demonstrating strong interfacial coupling and efficient electron transfer (from CS to MB). The unique piezocatalytic system operates under mild mechanical energy input (600 rpm), achieving an exceptional 80.36% HMF conversion with 78.00% DFF yield (97.07% selectivity) and an H₂ evolution rate of 0.147 μmol/(mg_catalyst·h). This substantial enhancement, which achieved a 2.7-fold increase in DFF formation kinetics and a 1.8-fold boost in H₂ generation over pristine CS, signifies a clear breakthrough in piezocatalytic systems for coupled biomass oxidation and proton reduction. Mechanistic investigations via ESR spectroscopy and DFT calculations reveal that carbon-centered radicals mediate the selective oxidation pathway, while the Schottky junction at the CS/MB interface enhances charge separation, thereby suppressing recombination. By replacing conventional thermal/chemical inputs with mechanical activation, this work pioneers a self-sustaining bio-refinery paradigm where piezoelectric polarization and catalytic active sites cooperate as a unified energy-harvesting reactor. This strategy demonstrates a promising potential pathway for simultaneously advancing green chemical synthesis and renewable energy production.