Upcycling electroless nickel plating wastewater to Ni2P-Ni9S8 catalyst for scalable electrosynthesis of 2,5-furandicarboxylic acid

Treating electroless nickel plating (ENP) wastewater is an energy and cost intensive process owing to its high content of phosphor, sulphur, and organic complexing agents. Here we demonstrated the solar-thermal evaporation of real ENP wastewater into clean water and solid composite, which was then converted to an efficient Ni 2 P-Ni 9 S 8 heterojunction electrocatalyst for the oxidation of biomass derived 5-hydroxymethylfurfural to valuable 2,5-furandicarboxylic acid (FDCA). This catalyst achieves high current up to 200 A in a 200 cm 2 continuous-flow reactor with 80.4% of Faradaic efficiency and 5.0 mmol cm −2 h −1 of production rate for FDCA electrosynthesis. Moreover, this reactor can be operated at 100 A with stable single-pass conversion efficiency (∼91%), Faradaic efficiency (∼86%) and selectivity (∼95%) of FDCA for 177 h, totally producing 14.7 kg of FDCA. This work showcases the integrated valorization of ENP wastewater and biomass platforms to valuable materials and chemicals driven by sustainable energy.