Photothermal hydrogen production from oxidative hydrolysis of electrochemically synthesized nano-sized zinc

Abstract Proof of concept is established for low cost, scalable and safe access of hydrogen via photo-assisted oxidative hydrolysis of nano-sized zinc (Zn NPs). The Zn NPs with diameter of 40–50 nm are electrochemically grown on copper plate in conventional three electrode system at applied bias of 0.7 V. These NPs have long-range absorptivity from Visible-NIR region and directly employed for photothermal hydrogen production. The highest H 2 production rates of 0.2 mmolh −1 and 0.43 mmolh −1 are observed under illumination of tungsten light and concentrated sunlight respectively. In addition, Zn nanoparticles have shown great potential for CO 2 photoreduction. Under CO 2 microenvironment and tungsten light illumination, maximum H 2 production rate of 0.3 mmolh −1 is achieved along with formation of 0.116 mgL −1 formic acid. The significant enhancement may attribute to zinc nanoscale dimension which eventuates the hydroxylation rate and also increases the localized temperature by oscillating its surface electrons in resonance with incident radiation.