Artificial Surface Electron Network Prompted Energy Band Structure Tuning: Boosting Solar-to-Hydrogen Evolution Performance

Abstract

The energy gap and conduction band position of catalysts play crucial roles in solar-to-hydrogen (STH) transformation technology. Unfortunately, although an increase in the conduction band position can effectively promote the photoreduction capacity of the photocatalyst, it will inevitably widen the band gap, thus reducing the light-absorption scale. It seems that there is a contradiction between the reduction of band gap and the improvement of conduction band position, which is that "You can't have your cake and eat it too." Herein, an ultrasimple molecular adsorption strategy was engineered by adsorbing hydrazine hydrate on the surface of TiO 2 . The theoretical and experimental results indicated that the strong electron-donating effect of amino groups in hydrazine hydrate can promote the redistribution of photogenerated electrons and form surface electron networks on the surface of TiO 2 photocatalysts, which can bend the conduction band upward and significantly improve its photoreduction ability. Besides, the adsorption of −NH 2 can narrow the band gap width of TiO 2 and promote the separation efficiency of photogenerated carriers. More interestingly, it can also effectively enhance the adsorption of H 2 O and H + , thus greatly elevating the STH efficiency. The STH rate of the as-prepared T−N−3 can be increased by ≈530%. This work sheds light on a new approach for resolving the contradiction between photoreduction and light absorption capabilities to effectively enhance photocatalytic performance.