Carbon dots regulate the multiple-proton-electron catalytic process and switch carbon dioxide reduction to hydrogen evolution reaction of PdCu alloy electrocatalyst

The switch from efficient CO2RR on PdCu alloy to HER on PdCu-CDs. [Display omitted] •The efficient ECO2RR on the surface of PdCu alloy with CDs turns into HER for the first time.•CDs can regulate the multi-electron and multi-proton catalytic process on well-defined active center.•The regulation of CDs on electron transfer and proton was in-depth studied by TPV. Electrocatalytic CO2 reduction reaction (ECO2RR) is a typical small molecule conversion reaction, which involves multiple-proton-electron coupling processes. As a typical competitive reaction, hydrogen evolution reaction (HER) competes with ECO2RR for protons, thus increasing the diversity of reaction paths. In this work, PdCu alloy is an effective electrocatalyst for ECO2RR. After the combination of carbon dots (CDs) with PdCu alloy, the highly efficient ECO2RR on the surfaces of PdCu alloy turns to HER for the first time. The strong adsorption of electrons and protons by CDs altered the reaction path on the PdCu for ECO2RR, as confirmed by a series of characterizations and transient photo-induced voltage tests, leading to the switch of ECO2RR to HER. This work verifies the important role of CDs in the regulation of electron transfer and proton, realizes the interference of the multi-proton and multi-electron catalytic processes on the well-defined active center (or one active center), and gives us a new insight to design the reaction paths.