Synthesis and electrochemical evaluation of nano-NiO-Y composite cathode material for hydrogen evolution in microbial electrolysis cell

Nano Y zeolites were synthesized by adding carbon spheres into the synthesis sol of Y zeolites subjected to aging and hydrothermal crystallization; nickel-salt precursors were then loaded by using an incipient-wetness impregnation (IWI) method. After calcination, the nano-NiO-Y composite were then characterized by means of XRD, SEM, TEM, XPS, TG-DTG, and N₂ adsorption-desorption techniques and its performance as the cathode material for hydrogen evolution in microbial electrolysis cell was then investigated. The results show that the nano-NiO-Y composite has a crystal size of 500 nm of size and multiple porous structure including micro and mesopores; the total surface area and pore volume of nano-NiO-Y composites are 774.3 m²/g and 0.495 cm³/g, respectively. The electrochemical tests of linear scanning voltammetry and Tafel plots show that as microbial electrolytic cell (MEC) cathode, the nano-NiO-Y composite with a nickel-salt loading of 30% exhibits high electrocatalytic activity. In a continuous operation cycle, the largest hydrogen evolution current density of the nano-NiO-Y composites reaches 22.87 A/m², and the H₂ content is about 73.71% in total gas. The hydrogen production efficiency is 0.393 m³/(m³·d), comparable to that of Pt/C cathode.