Solar hydrogen production of ZnO horn electrodeposited on carbon film

• Single crystalline ZnO horn was electrodeposited on carbon films (CF).
• ZnO/CF and ZnO/ACF produced hydrogen more than that of bare ZnO nanoparticle.
• ZnO/ACF had the highest hydrogen production rate with the value of 3.800 µmol h−1.
• Fast electron transfer of CF had a key role in photocatalytic hydrogen production.

Solar hydrogen production by ZnO electrodeposited onto carbon films was systematically investigated by controlling the amount of the deposited ZnO, property of carbon, and surface activation by KOH treatment. Carbon films have been prepared by polymer solution casting method using PAN solution, and subsequently annealing process. The surface of carbon film became made more porous by chemically activating using KOH. And then, by electrochemical deposition, single crystalline ZnO horn was loaded on both carbon film and activated carbon film to ZnO-based hetero photocatalysts. Electrochemical deposition has been carried out to investigate the effect of ZnO-loading amount by varying deposition condition such as deposition time and concentration of zinc acetate solution. The size of ZnO horn deposited was highly dependent on initial concentration of Zn precursor and deposition time. The measurement of hydrogen production showed that photocatalytic ZnO has produced hydrogen 1.65 and 1.68 times more when deposited on non-activated carbon film and activated carbon film, respectively, than ZnO nanoparticle alone, on account of fast electron transfer due to high electrical conductivity of carbon film. Whereas, by chemically activating carbon film to activated carbon film through the base treatment, hydrogen production was increased only 1.02 times as much as that by ZnO deposited on non-activated carbon film. In this work, the results were discussed and reasoned and it was suggested that characteristics of carbon film would play the most important key role on enhancement of hydrogen production using ZnO-based hetero photocatalysts among various factors.