Plasma-Processed Ni-Based Catalytic Film for Urea Oxidation Reaction

Electrocatalytic water splitting for H2 generation and CO2 electroreduction in chemical production play crucial roles in sustainable energy systems. However, the oxygen evolution reaction (OER) at the anode poses a challenge due to low energy conversion efficiency, limiting broader practical applications. An alternative anodic reaction with high thermodynamic favorability is the urea oxidation reaction (UOR). Unfortunately, current highly efficient nickel-based catalysts face challenges related to dependence on specific nickel oxidation states and passivation reactions at high potentials, rendering urea oxidation inefficient and impractical.

In our recent investigation, we employed advanced characterization techniques, encompassing in-situ electrochemical impedance spectroscopy, in-situ Raman spectroscopy, quasi in-situ X-ray diffraction (XRD), quasi in-situ X-ray photoelectron spectroscopy (XPS), and post-reaction characterization to scrutinize the conventional Ni-based catalytic film. Our exploration delved into comprehending the characteristics of Ni(OH)2 and analogous compounds such as NiFe-LDH under anodic reaction conditions, encompassing their electrochemical behavior and materials evolution. Mechanisms such as the transfer of catalytic active sites with material phase transitions and the reasons for passivation reactions at high potentials were discussed. Furthermore, we incorporated plasma etching techniques and implantation methods to modify the catalysts, enhancing their catalytic activity, particularly in terms of achieving high current output at elevated voltages. Utilizing the modified catalytic electrodes, the assembled urea oxidation coupled hydrogen production device exhibited excellent energy-saving and passivation-avoidance characteristics, highlighting the application potential of the prepared catalytic electrode.

Overall, our work provides both theoretical and experimental evidence supporting the rational design and improved utilization efficiency of catalysts. Additionally, our findings suggest that plasma treatment emerges as a valuable tool for materials modification, altering the electrochemical properties of catalysts.