Charge storage of carbon dot enhances photo-production of H2 and H2O2 over Ni2P/carbon dot catalyst under normal pressure

Photo-production of hydrogen (H2) and hydrogen peroxide (H2O2) simultaneously from water catalytic-splitting has received widespread attention. Most photocatalysts suffer from H2O2 poisoning and rapid recombination of photogenerated electrons and holes. Although photocatalysts against H2O2 poisoning have been prepared, the long-time stability of photogenerated electrons is still a great challenge. Here, we demonstrate that carbon dots (CDs) can stabilize and store the photogenerated electrons, promote the effective separation of photo-generated charges, and improve the photocatalytic activity and stability of the catalyst. The Ni2P/CDs composite photocatalyst synthesized in this work can produce H2 and H2O2 simultaneously under atmosphere, and the yields of H2 and H2O2 can reach 258.6 μmol/h/g and 1281.4 μmol/h/g, respectively. It represents the highest yield of H2O2 ever reported in photocatalysts capable of producing both H2 and H2O2 simultaneously under normal pressure. This work provides some deep insight on the storage and stability of photogenerated electrons, and open up a new way for the high efficient photocatalyst design based on the regulation of the interface charge dynamics.