Effective Low-Temperature Methanol Aqueous Phase Reforming with Metal-Free Carbon Dots/C₃N₄ Composites

Methanol aqueous phase reforming (MAPR) reaction under mild conditions is one of the most practical ways to generate hydrogen (H₂), in which the liquid vaporization unit could be removed by the water phase reforming, making the structure of an in situ H₂ production reactor more compact. In this work, the H₂ production performances of the metal-free catalyst, N-doped carbon dots/g-C₃N₄ (NCDs/g-C₃N₄; CN-x) composites, was investigated for the MAPR reaction under low temperature and normal pressure. The optimized metal-free catalyst (NCDs/g-C₃N₄; CN-0.7) displays a H₂ yield of 19.5 μmol g^-1 h^-1 at 80 °C. More importantly, a clear understanding on the effective MAPR reaction at low temperature and normal pressure was acquired from in situ diffuse reflectance FTIR spectroscopy and the transient photovoltage test. The introduction of NCDs leads to the localization of surface charge, which is beneficial to the selective adsorption and polarization activation of polar molecules on the catalyst surface. This work provides a new strategy for the carbon-based catalyst design of the MAPR reaction at low temperatures.