Nickel-based non-noble metal layered double hydroxide grown on carbon cloth for boosting electrocatalytic oxidation of As(III)

The novel non-noble metal anodes of Ni-based (Co 2+ , Fe 2+ , and Mn 2+) layered double hydroxides (Ni-based LDH) were uniformly anchored on the carbon cloth (CC) surface (denoted as Ni-based LDHs/CC) by a simple, rapid and universal electrodeposition approach. The low-cost NiCo-LDH/CC anodes not only possessed superior conductivity and more exposed reactive sites, but also delivered promising electrocatalytic oxidation ability. Notably, the electrocatalytic oxidation efficiency of the obtained NiCo-LDH/CC and NiMn-LDH/CC anodes were positively correlated with the deposition amount of NiCo-LDH and NiMn-LDH, wherein NiCo-LDH-180s/CC anode delivered a significant enhancement in electrocatalytic oxidation efficiency of As(III), over 4.7 times higher than that of pure CC. Impressively, the NiCo-LDH-180s/CC anode exhibited larger electrochemical active areas and outstanding electrocatalytic activity, and can achieve nearly 100% conversion efficiency within 20 min at a current density of 6 mA/cm 2 . In particular, the developed anode is also distinguished by its adaptability to different pH values and its strong immunity to coexisting ions, which is expected to be widely applied in various As(III)-contaminated environments. Electron spin resonance spectra fully validated the formation of free radicals (•OH and •O 2 − ) with strong oxidative properties, and was employed to further investigate the associated reaction mechanism in combination with quenching experiments. This work potentially offers an in-depth perspective of electrocatalytic technology for the decontamination of highly toxic As(III) wastewater through cost-effective non-noble metal anodes and broadens the scope of electrocatalysts.