Enhanced electro-activity of nickel phosphide by pre-treatment for efficient hydrogen sulfide elimination

Abstract

Electrochemical sulfide oxidation is a promising approach for sulfide removal from wastewater or biogas due to low energy and chemical consumption. In this work, nickel phosphide was facilely electrodeposited on stainless steel (SS/Ni-P) and comprehensively evaluated as anode catalyst for sulfide oxidation. Electrochemical property analysis suggested that SS/Ni-P had low polarization resistance (109.10 Ω) and high electrochemical active surface area (Cdl = 1.3 mF/cm2). The sulfide removal efficiency of SS/Ni-P achieved 95.00 ± 3.55 % at 1.42 V vs RHE within 48 h, which was 2.60 times and 3.62 times of that by SS/Ni and SS anodes, respectively. The first order kinetic rate constant of SS/Ni-P for sulfide removal was 0.0315 ± 0.0061 h-1, superior than that of the reported single nickel atom based catalyst with stainless steel substrate. Pre-treating SS/Ni-P under a constant external potential for 10 s further improved the electroactivity on sulfide oxidation due to the enhancement of the electrochemical active surface area by 46.56%. Further analysis of the chemical state changes during the sulfide oxidation process revealed that the Ni from Ni-P was the real active center, which formed Ni-S precursors to promote polysulfide formation. This work provided a highly efficient sulfide oxidation anode material for sulfide containing wastewater and biogas treatment.