Oxygen vacancies engineering in TiO2 homojunction/ZnFe-LDH for enhanced photoelectrochemical water oxidation

The high-efficiency separation and transfer of photogenerated electrons and holes are significant to achieve highly photoelectrochemical water redox efficiency. Here, we integrate anatase TiO2 with moderate oxygen vacancies and ZnFe-LDH cocatalyst on 3D homojunction r-TiO2(rutile TiO2)/a-TiO2(anatase TiO2) photoanode to promote the separation and transfer efficiency of carriers for a high photoelectrochemical activity. The as-prepared r-TiO2/a-TiO2/ZnFe-LDH photoanode demonstrates an enhanced photocurrent density of 1.86 mA cm−2 at 1.23 V vs. RHE and the onset potential of 0.26 V vs. RHE, 2.55 times and 100 mV cathodic shift by contrast with those of bare r-TiO2. The experimental and calculated results suggest the improved electron transport by oxygen vacancies and r-TiO2/a-TiO2 with matched energy bands, along with the accelerated hole capture and facilitated surface oxygen production reaction kinetics by cocatalyst ZnFe-LDH. The compare researches for the sample without the oxygen vacancies are introduced to further illustrate the increased carrier concentration and conductivity caused by oxygen vacancies. This work manifests the effective use of oxygen vacancies in regulating carriers transport and provides a novel strategy for manufacturing high-performance photoanodes in photoelectrochemical water splitting.