Electronic Structure-Engineered Copper-Doped MoS2 for High-Efficiency Indigo Electrocatalytic Hydrogenation: A Sustainable Platform for Denim Dyeing

The conventional denim dyeing industry faces growing sustainability challenges due to its reliance on sodium dithionite (Na 2 S 2 O 4 )-mediated indigo reduction, which generates over 15 t of sulfate/sulfite waste per ton of fabric. To address these issues, we propose an electronic structure engineering strategy via copper (Cu) atomic doping to develop high-performance molybdenum disulfide (MoS 2 ) electrocatalysts for sustainable indigo hydrogenation. Density functional theory (DFT) calculations reveal that Cu doping reconstructs the hybridization of S 2p orbitals, elevating the density of states (DOS) near the Fermi level and downshifting the S p-band center. This electronic reconfiguration enhances the carrier concentration, accelerates interfacial charge transfer kinetics, and activates the catalytically inert MoS 2 basal plane. Concurrently, the lowered ε p energy level intensifies active hydrogen (H*) adsorption at S sites and amplifies Mo sites’ anchoring effect on indigo molecules, synergistically optimizing electrocatalytic hydrogenation (ECH) pathways. The optimized 2Cu-MoS 2 –CF electrode achieves 85.56% indigo conversion efficiency at a 40 g/L dye concentration with 82.32% Faradaic efficiency. Notably, this system elevates fabric color strength ( K / S value) by 11.5% versus conventional Na 2 S 2 O 4 -based processes while retaining ISO 105-A02 washing fastness (>4/5 rating). Furthermore, the catalyst demonstrates robust operational stability, sustaining >93% initial activity over 15 consecutive dyeing cycles (Δ K / S < 7%). Industrially, this approach reduces energy consumption by 33.08% and operational costs by 21.59%, while generating a biodegradable effluent (BOD/COD = 0.41), addressing both economic and environmental bottlenecks. Our work establishes a charge-transfer-driven catalyst architecture, bridging atomic-scale electronic engineering to scalable green textile manufacturing, with transformative potential for sustainable denim production.