Constructing heterogeneous structure to improve the redox ability of Nb2O5 photoanode and effectively actuate carrier separation for efficient photoelectrochemical water splitting system

Niobium-based oxide semiconductors face the problems of narrow photo-response range and fast carrier recombination in the field of photoelectrochemical (PEC) water splitting. Based on the above problems, we chose the idea of constructing a heterojunction and successfully loaded Ag2O onto Nb2O5 photoanode by ion precipitation to effectively enhance the carrier separation efficiency and broaden its photo-response range. The results show that the composite electrode NA-3 exhibits excellent photoelectrocatalysis performance under illumination and bias voltage. The photocurrent density was increased to 0.481 mA/cm2, approximately 2.88 times that of the Nb2O5 photoanode, and a negative onset potential shift of 139 mV was achieved. The higher ABPE and IPCE values of composite electrode indicate its higher catalytic conversion ability and quantum efficiency. The Mott-Schottky results reveal that the loading of Ag2O not only causes a negative shift of Vfb, improves Faraday transfer efficiency, but also reduces WDep at the electrode/electrolyte interface, effectively improving the photocatalytic performance of the photoanode. This work promotes the development of Nb2O5 materials in the field of PEC water splitting through the idea of constructing heterojunctions, and provides an effective strategy for suppressing carrier recombination to achieve highly active photoanodes.