Large‐Scale Sulfur Quantum Dots Production Coupled With Hydrogen Evolution Via Electrochemical‐Chemical Tandem Synthesis

ABSTRACT

Production of value‐added chemicals and materials through electrochemical processes represents a game‐changing synthetic route, yet its scalability has not been demonstrated. Here, we report a tandem electrochemical‐chemical process that converts aqueous sulfide feedstocks into sulfur quantum dots (SQDs) while co‐producing hydrogen. Based on cost‐effective, commercially available Ni ₃ FeMo _0.1 powders, a heterostructured Ni ₃ FeMo _0.1 @NiTe ₂ catalyst is developed, which drives the electrochemical sulfide‐to‐polysulfide oxidation reaction at current densities up to 1.0 A cm ⁻² with a voltage of only 1.07 V in natural seawater electrolyte at 80°C, and achieves stable operation for over 290 h in the membrane electrode assembly while maintaining excellent performance in four‐cell electrolyzer stacks with a SQD yield rate of 142 mg cm ⁻² day ⁻¹ . Operando spectroscopy investigations and density functional theory calculations reveal that multi‐metal electronic delocalization around Ni, Fe and Mo active centers confines sulfidation to the catalyst surface and stabilizes a higher surface sulfur coverage, thereby lowering the energy barrier to the rate‐determining step while suppressing bulk NiS formation. The resulting SQDs exhibit excitation‐dependent photoluminescence tunable across the violet‐to‐blue region. This work demonstrates surface‐reconstruction engineering as a rational catalyst‐design principle for coupled electrosynthesis of nanomaterials and green hydrogen, and moreover, it showcases scale‐up synthesis of SQDs with tunable photoluminescence.