An organic–inorganic hybrid polyoxoniobate decorated by a Co(iii)-amine complex for electrocatalytic urea splitting

Abstract

The overall energy efficiency of electrochemical systems is significantly reduced by the conventional anodic oxygen evolution reaction (OER). It is feasible to improve energy efficiency by replacing the OER with the urea oxidation reaction (UOR), which has a lower thermodynamic potential. An organic–inorganic hybrid polyoxoniobate decorated by a Co(III)-amine complex, Na₄(H₂O)₁₅[Co(en)₃]₂{[Co(en)(Nb₆O₁₉)]₂}·34H₂O (Co₂Nb₆, en = ethylenediamine) with distinct physicochemical characteristics and well-defined single-crystal structure is reported. The structure of Co₂Nb₆ contains Lindqvist {[Co(en)(Nb₆O₁₉)]₂}¹⁰⁻ dimer and free [Co(en)₃]³⁺ complexes. Co₂Nb₆ exhibits remarkable catalytic activity for the UOR after being firmly attached to the surface of acetylene black by polyethyleneimine (PEI). To the best of our knowledge, this is the first instance of performing the electrocatalytic UOR based on Lindqvist polyoxoniobate clusters, which will pave the path for innovative concepts in the development of POM-based electrocatalysts.