IrO2-TiO2 electrocatalysts for the hydrogen evolution reaction in acidic water electrolysis without activation

The development of highly active and long-term stable electrocatalysts for the hydrogen evolution reaction (HER) is very important. Because of the hysteresis phenomenon, IrO2 is rarely used as a cathode material for the HER. Herein, an IrO2-TiO2 composite oxide was prepared using the thermal decomposition method. The physical and electrochemical characterization of the materials was achieved by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the process of the HER, the current of IrO2 is only 1.91 mA cm(-2)@-0.2 V in the first segment scan. However, at the 51, 101 and 151 segment scan, the HER current increases to 6.85, 15.7 and 18.2 mA cm(-2)@-0.2 V, respectively. During the activation process of IrO2, the HER current has increased ten times. Compared with the HER activity of IrO2, there is almost no hysteresis for the IrO2-TiO2 electrode. In the first segment scan, the HER current has already reached 27.9 mA cm(-2)@-0.2 V and further increased to 31.1, 33.1 and 35.0 mA cm(-2) at the 51, 101 and 151 segment scan. The difference between them is not significant, which means that the IrO2-TiO2 electrode does not need activation. The IrO2-TiO2 electrode has exhibited a higher HER activity than the IrO2 electrode, which may be attributed to the electronic structure modification and the increase of the electrochemical area.