Noble-metal-free 3D hierarchical Ni-WC heterostructure with enhanced interfacial charge transfer for efficient electrocatalytic hydrodechlorination

Abstract

Electrocatalytic hydrodechlorination (EHDC) provides a promising approach to efficiently remove the halogenated organic pollutants in water. Herein, a kind of noble-metal-free three-dimensional (3-D) hierarchical nickel-tungsten carbide (Ni-WC) heterostructure supported on nickel foam (NF) (Ni-WC/NF) was fabricated via the in-situ hydrothermal growth and annealing treatment of Ni,W-rich polyoxometalate {Ni54W72}. Featuring self-supported 3-D hierarchical skeleton structures and abundant Ni-WC interfaces, Ni-WC/NF exhibited high-efficient EHDC performance towards 4-chlorophenol (4-CP) with 100 % conversion efficiency in 3 h, large reaction rate constant of 2.2 × 10-2 min−1 and high current efficiency of 13.9 %, which is comparable to the-state-of-the-art Pd-based catalysts. The active atomic hydrogen (H*) generation kinetics and the interactions of Ni-WC heterostructure with 4-CP/phenol were evaluated. DFT calculations demonstrated that the coverage of 4-CP determines the EHDC efficiency, the Ni-WC heterostructure optimizes the electronic structure of Ni, enhances the adsorption of 4-CP and facilitates the desorption of phenol, thus promoting EHDC performance. This work provides an efficient noble-metal-free catalyst for enhanced electrochemical dechlorination in organic-pollutant treatment.