Electrically Conductive Ni-P Nanoporous Membrane Reactors for Electrochemical Reductive Dechlorination of Organic Pollutants

Abstract

Transition-metal phosphides (TMPs) are emerging electrocatalysts for both hydrogen evolution and the conversion of reactants/contaminants by various electrochemical reactions. TMPs are promising catalysts because they are earth abundant, have high electrical conductivity, and have high chemical stability. In this seminal work, a low-priced nickel phosphorus (Ni-P) ultrafiltration membrane was fabricated and used for electrochemical reductive dechlorination of chlorophenols. Amorphous Ni-P nanoparticles were grown on an ultrafiltration poly(ether sulfone) (PES) membrane via electroless deposition. The prepared Ni-P membrane was used as a cathode for electrochemical reductive dechlorination of 2-chlorophenol (2-CP) in flow-through mode. It was observed that a dechlorination efficiency of 42.7%, a reaction rate constant of 1.621 min–1, and a Faradaic efficiency of 24.5% were achieved at an optimized cathodic potential of −2.50 V. The dechlorination was primarily attributed to the partial positively charged Niδ+ on the Ni-P membrane surface, which facilitated atomic H* evolution by forming reactive Ni–H* bonds for dechlorination. Additionally, doping P atoms in Ni retarded the deactivation of electrocatalytic Ni sites. This work demonstrates that the cost-effective Ni-P membrane electrocatalyst is a promising technology to degrade chlorinated compounds with applications to industrial wastewaters and landfill leachates.