Pd/Ni(OH)2/Ni foam: A nickel-based composite electrode for the electrochemical reductive remediation of trichloroethylene-contaminated groundwater

Abstract

Based on the remediation challenges and practical needs of trichloroethylene (TCE)-contaminated groundwater, this study prepared an Ni-based composite electrode, Pd/Ni(OH)₂/Ni foam (NF), and evaluates its electrocatalytic degradation effect on TCE in a groundwater environment. Under an applied voltage of –1.3 V versus Ag/AgCl, the TCE removal rate reaches 92 % after 1 h of electrolysis. The introduction of Ni(OH)₂ nanoarrays accelerates the electron transport process, shortens the ion transport distance, and significantly increases the electron density of Pd. Furthermore, TCE is rapidly reduced by adsorbed hydrogen radicals on the Pd surface, and the ethane conversion rate reaches 62 %. The experimental results show that the electrode can maintain a strong electrocatalytic activity over a wide pH range (3–9) and that it is not affected by common anions, such as Ca²⁺, HCO₃^-, SO₃^2-, or Cl^-, in groundwater. Pd/Ni(OH)₂/NF exhibits a high reactivity after six cycles of use. The remediation mechanism is studied by combining the microscopic characterization of materials, electrochemical activity testing, and process product identification, which provides an effective way of completely degrading chlorinated hydrocarbon pollutants in natural groundwater environment.