Three-dimensional TiO2 nanobelt array with a disordered surface and oxygen vacancies for boosted photoelectrochemical water splitting†

The exploitation of photoelectrode materials with high-efficiency utilization of solar light, an outstanding separation property of photogenerated charges and a large surface area is extremely important yet significantly challenging. Herein, a three-dimensional array of reduced TiO₂ nanobelts with a disordered surface and abundant oxygen vacancies was successfully constructed for PEC water splitting. As expected, the reduced 3D-TiO₂ nanobelt array produced a photocurrent density of 0.96 mA cm⁻² at 0.22 V vs. Ag/AgCl with a faradaic efficiency of 100%, corresponding to 2.4 times enhancement compared with that of the pristine 3D-TiO₂ nanobelt array. Furthermore, IPCE was improved within both the UV and visible light regions. This enhancement originates primarily from the efficient utilization of UV-visible light as well as the promoted separation and transport of photogenerated charges induced by the cooperative effect of the disordered surface and oxygen vacancies. This research sheds new light on exploiting TiO₂ nanobelts for PEC applications.