Heterometallic Polyoxotitanium Clusters as Bifunctional Electrocatalysts for Overall Water Splitting.

Incorporating heterometal into titanium-oxygen clusters (TOCs) is an effective way to improve its catalytic activity. Herein, we synthesize three novel heterometallic TOCs with the formula of [TiCuO(Dmg)(OAc)(PrO)][HTiCuO(Dmg)(OAc)(PrO)] (), [TiCuO(Dmg)(OAc)(PrO)] (), and [TiCoO(Dmg)(Pdc)(PrO)Cl] (, DmgH = dimethylglyoxime; PdcH = pyridine-2,3-dicarboxylic acid) using dimethylglyoxime and different carboxylates as the synergistic ligands. By depositing the clusters and on carbon cloth as electrodes, we investigated the electrocatalytic performance of TOCs for full water splitting for the first time. To reach a 10 mA cm current density in an alkaline solution, the @CC electrode needs an overpotential as low as 120 and 400 mV for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), respectively. In addition, full water-splitting equipment with @CC as a cathode and an anode need only 1.67 V to deliver a current density of 10 mA cm. Our work confirmed the potential of noble metal-free TOCs as bifunctional cluster-based electrocatalysts for water splitting, and their activities can be tuned by doping with different metal ions.