Synergistic electronic modulation via Sn/P dual-doping engineering enables robust bifunctional electrocatalysis in complex wastewater systems

The integration of environmental remediation with green hydrogen production bifunctional water electrolysis in hypersaline industrial effluents requires catalysts that simultaneously address efficiency-stability trade-offs. This study presents a self-supported P-SnCoFe-LDH/NF architecture engineered through dual-ion co-doping, demonstrating unprecedented performance in chloride-rich alkaline oilfield wastewater. The optimised catalyst achieves overpotentials of 253 mV for oxygen evolution reaction (OER) and 187 mV for hydrogen evolution reaction (HER) at 10 mA cm −2 with 12-h stability, representing a 4 and 41 % performance retention improvement over conventional CoFe-LDH in aggressive media. Mechanistic studies reveal dual electronic modulation: Sn-doping induces d-band center downshifting while P-incorporation generates electron-deficient metal centers. This synergy establishes optimal adsorption–desorption equilibrium, evidenced by 21 % reduced OER charge transfer resistance and 56 % enhanced HER Volmer kinetics. The symmetric electrolyser (P-SnCoFe-LDH/NF||P-SnCoFe-LDH/NF) maintains <2 % voltage decay during continuous operation. This work presents a new paradigm for multifunctional electrocatalysis in complex aqueous matrices.