Strategies for the structural tuning of inorganic-organic hybrid materials are crucial for their technological application. We present a ligand replacement strategy for NiClOH-PmxPz1-x inorganic-organic hybrid nanorods (Pm = pyrimidine, Pz = pyrazine) to improve their performance in urea-assisted water oxidation reaction. Through the partial substitution of pyrimidine ligands with pyrazines, significant oxygen vacancies on the surface of NiClOH-Pm nanorods were introduced, while improving electrocatalytic performance through additional π-π interaction between ligands. The composite material exhibits excellent performance in electrocatalytic urea oxidation, with a higher electrochemical double layer capacitance (23.8 mF cm-2) and a small Tafel slope (41.9 mV dec-1), reaching potentials of 1.37 and 1.53 V at 10 mA cm-2 and 100 mA cm-2, respectively. The optimized ligand ratio (Pm/Pz = 33/1) enhances π-π interactions, which improves electron transferring between ligands and Ni centers, and thereby the catalytic efficiency. DFT calculations show that the adsorption of Ni on urea takes precedence over the adsorption of OH- during the electrocatalytic process. This work offers a design strategy to improve the electrochemical performance of hybrid inorganic-organic materials through substitutional ligand design.
Meng et al. (Fri,) studied this question.