Rationally tuning the active sites of copper-based catalysts towards formaldehyde reforming into hydrogen

Abstract

Direct splitting of liquid organic fuels using a particulate catalyst is an effective way to produce hydrogen on a large scale. Here, we report a simple and reliable method for the synthesis of a Cu/MgO catalyst and its potential for aqueous-phase formaldehyde reforming into H₂. Experimental observations reveal that the chemical state of Cu species could be finely tuned by altering the partial pressure of oxygen, thereby affecting the catalytic activity of the Cu/MgO catalyst. In detail, a highly reactive Cu(0) species is formed via the in situ reduction of CuO with oxygen, which is vital to the structural stability and the active sites exposure of the catalyst. Additionally, the adsorption of oxygen is synergistically optimized at the heterointerface, benefiting the breaking of C–H bonds in HCHO and substantially accelerating the hydrogen production kinetics with the generation of ˙OOH radicals. Under aerobic conditions in neutral media, the resulting catalyst liberates H₂ with exceptional turnover frequencies (TOF, 320.71 h⁻¹) and improved stability. The present work offers opportunities for the efficient conversion of liquid organic fuels into H₂ under ambient conditions.