Wet Treatment of Ni-Containing Electroplating Wastewater Doped with Fe and Co as a Hydrogen Evolution Catalyst

We propose a process for treating nickel-plating wastewater and using the products directly as hydrogen evolution reaction catalysts. First, the wastewater is soldered to remove sodium salts and then evaporated and concentrated. Next, Ni/Fe(OH)2 and Ni/Co(OH)2 laminar metal composites are prepared by membrane electrolysis. NiFe2O4 and NiCo2O4 are obtained by calcination of the electrolytic products. The results indicated that Ni/Co(OH)2 has the largest specific surface area (170.3 m2/g) and a typical nano-layered structure. Their electrocatalytic performance for hydrogen evolution in an alkaline solution was evaluated. Compared with reversible hydrogen electrodes, Ni/Fe(OH)2, Ni/Co(OH)2, NiFe2O4, and NiCo2O4 exhibited excellent hydrogen evolution reaction catalytic activity. The Tafel slopes are 104.2, 96.5, 133.9, and 176 mV, and the overpotentials are 507.1, 387.9, 545.5, and 412.1 mV, respectively. In addition, the catalyst NiCo2O4 showed good stability after 14 h. Therefore, NiCo2O4 is expected to be a practical non-noble metal material as a catalyst for hydrogen evolution reactions.