Enhanced photoelectrochemical activity and photocatalytic water oxidation of NiO nanoparticle-decorated SrTiO3 nanocube heterostructures: Interaction, interfacial charge transfer and enhanced mechanism

• NiO@STO nanocrystal@nanocube heterostructures were firstly fabricated.
• NiO@STO nanocrystal@nanocube heterostructures exhibit the enhanced PEC activity.
• NiO@STO nanocrystal@nanocube nanostructures show superior water oxidation activity.
• Interaction, charge transfer and enhanced mechanism of photocatalyst were proposed.
• p–n Junction and inner electronic field drive the photoexcited charges separation.

Here we demonstrate the enhanced photoelectrochemical (PEC) performance and photocatalytic activity towards water oxidation of n-type SrTiO3 (STO) nanocubes coupled with p-type NiO nanoparticles (denoted as p-NiO@n-STO nanoparticle@nanocube), fabricated by calcining Ni(NO3)2-loaded STO nanocubes. High resolution transmission electron microscope studies show that intimate p–n junctions are formed between n-type STO and p-type NiO interfaces. As a p–n junction photoanode, the p-NiO@n-STO nanoparticle@nanocube nanostructures exhibit the enhanced PEC activity and photocatalytic water oxidation. The photocurrent density of the p-NiO@n-STO nanostructure electrode reaches 3.5 µA cm−2, which is 7 times higher than that (0.5 µA cm−2) for pure STO nanocube electrode at 0 V versus Ag/AgCl. The p-NiO@n-STO nanoparticle@nanocube nanostructures also exhibit pronounced photoresponse to generate O2. The O2 generation is about 100 µmol after irradiation 3 h with a 300-W Xenon lamp, which is about 1.7 times higher than that (60 µmol) of pure STO nanocubes. The intimate p–n junctions between p-NiO and n-STO interfaces accelerate holes migration from valence band of n-STO to that of p-NiO and reduction of the recombination of electron–hole pairs by the internal electrostatic field in the interface, which are believed to be the main reasons for enhanced PEC response and water-splitting performance of the as-prepared p-NiO@n-STO nanoparticle@nanocube nanostructures. The present work demonstrates that the p–n junction p-NiO@n-STO heterostructures have great potential applications in the field of photoelectrical devices and photocatalysis for water splitting.