Solvent-engineered NiMo-based electrocatalysts for simultaneous hydrogen evolution and PET plastic waste upcycling

The massive accumulation of polyethylene terephthalate (PET) plastic waste urgently requires sustainable resource recovery strategies. Conventional PET recycling struggles with efficiently valorizing ethylene glycol (EG), a major depolymerization byproduct, limiting economic viability and material circularity. This study designs NiMo bifunctional electrocatalysts via a solvent-modulated strategy to synergistically drive hydrogen evolution (HER) and EG oxidation (EGOR) for integrated plastic upcycling and green H₂ production. By adjusting water/EG ratios, precise control over phase composition and nanostructure evolution is achieved, governed by solvent-polarity-dependent dynamic reconstruction. Water-rich synthesis yields NiMo-W₃₀ nanorods with optimized hydrogen adsorption kinetics, delivering exceptional HER activity (η₁₀ = 8.21 mV, Tafel slope = 36.5 mV dec⁻¹). Conversely, EG-dominated synthesis produces ultrathin NiMo-W_0.5EG_29.5 nanosheets, where in situ Mo leaching generates Ni³⁺-rich active sites, achieving 93 % selectivity for formic acid via selective EGOR. A membrane electrolyzer integrating these catalysts concurrently upgrades 10 g PET into 8.43 g terephthalic acid and 7.76 g potassium diformate while generating 94.86 mmol H₂ at 1.58 V, surpassing conventional water splitting by 208 mV. Techno-economic analysis confirms a net profit of $244 per ton of PET treated, contrasting sharply with the $261 loss of traditional water electrolysis. This work establishes a closed-loop paradigm for plastic valorization and sustainable catalyst design.