Enhancing photocatalytic hydrogen generation on TiO2 using thermally derived nickel-based cocatalysts from Hofmann-type cyanide coordination polymer flakes.

We report herein a versatile method for synthesis of nickel-based inorganic compounds (i.e., Ni–O, Ni–S, Ni–Se, and Ni–P) from one basic nickel-cyanide-bridged coordination polymer (Ni-CP) flakes via a straightforward one-step annealing operation. Thus obtained Ni-based cocatalysts have been loaded over TiO 2 via facile incipient impregnation method to investigate performance towards H 2 production via H 2 O splitting reaction. Among examined compounds, the optimized 0.5Ni-P@TiO 2 exhibited the best photocatalytic activity with a hydrogen generation rate of 7.32 mmol h−1 g−1 compared with pristine TiO 2 (0.086 mmol h−1 g−1). While the 4Ni–Se@TiO 2 has revealed the strongest durability with cumulative hydrogen amount of 48.6 mmol g−1 upon a 5-h reaction, which is 81-fold higher than TiO 2 at identical conditions. On the other hand, Ni–S, Ni–P, and Ni–O, impregnated with 0.5 wt% of titania, show 13, 46, and 49-fold enhancement in evolved H 2 amount higher than the bare titanium dioxide. Additionally, the mixtures have been investigated again through photo-electrochemical measurements confirming the outperforming performance of Ni–P@TiO 2 (0.5% wt). The processed synthesis methodology is economical and easy opening a door to synthesizing various transition metal compound/semiconductor composites for efficient water photocatalytic hydrogen generation. [Display omitted] • Hydrogen extracted from water considered as a future fuel because of its sustainability and cleanliness. • The problem of huge energy required to split H–OH bond in water can be overcome through. • Among several approaches to produce green hydrogen from water, photocatalysis is the completely sustainable and eco-friendly approach. • Herein, we synthesized four nickel compounds from one parent Ni-CP, and investigated their influence on titania photocatalytic properties via water-splitting reaction. • 0.5Ni-P@TiO 2 composite provided the highest HGR (7.3 mmol h−1 g−1) with excellent electrical characteristics, while 4Ni–Se@TiO 2 composite gave the highest cumulative H 2 amount (48.6 mmol g−1), which indicated its distinguished stability. [ABSTRACT FROM AUTHOR]