Visible light driven photo-reduction of Cu 2+ to Cu 2 O to Cu in water for photocatalytic hydrogen production.

Metal nanoparticles are synthesized via various methods and have found many applications in areas such as sensing, electronics and catalysis. Light induced formation of noble metal nanoparticles, especially platinum, in solution or loaded on semiconductor surfaces, is an established practice in photocatalysis. Nevertheless, preparation of catalytically-active non-precious metal nanoparticles via photo-reduction still have room to be further explored. Here, we report a visible light driven system that can coordinate photo-reduction of CuSO 4 to selectively prepare Cu 2 O or Cu nanoparticles, while at the same time, mediating efficient hydrogen production with in situ generating Cu catalyst without further need to add any components. The Cu 2 O and Cu nanoparticles in situ generated are crystalline in nature and can perform as pre-catalyst (Cu 2 O) or catalyst (Cu) to catalyze hydrogen production when reincorporated into the same photo-reduction system with organic photosensitizers. Our work offers an exploratory pathway to prepare target metal nanoparticles while provides some insight into harnessing solar energy for multi-functional purposes.