Dolomite-supported Cu2O as heterogeneous photocatalysts for solar fuels production

The photocatalytic conversion of CO2 is a sustainable process to produce solar fuels. Also, this process would help to reduce the CO2 concentration to mitigate the global temperature and could partly fulfill energy demands. To achieve this, Cu2O photocatalyst represents an excellent option to convert the CO2 molecule into solar fuels. However, its capacity to adsorb CO2 is limited. Thus, it is necessary to support the photocatalyst in materials that provided strong basic active sites to adsorb CO2 spontaneously. In this case, dolomite is an earth-abundant material that contains alternating planes of Ca2+ and Mg2+ with the potential to be used as photocatalyst-support. Herein, for the first time, Cu2O was supported on an activated-dolomite via a microwave-hydrothermal method. The resulting materials were characterized by XRD, SEM, HRTEM, PL, FTIR, DRS, N-2 physisorption, and Raman spectroscopy. Cu2O supported on activated-dolomite (Cu/DA) was evaluated in the photocatalytic CO2 conversion to solar fuels (CH3OH and HCOH) under LED-visible light, and its capacity to adsorb CO2 was evidenced by gas chromatography. The dolomite-activated sample (DA) exhibited high surface area (125 m(2) g(-1)), low spherical and homogeneous particle size (200 nm), and small pore diameter (<2 nm), which contribute to a high amount of CO2 adsorbed (180 mg(CO2) g(-1)). This result was also related to the presence of the crystalline phases presented (Mg(OH)(2) and SiO2) in the DA sample. Regarding solar fuels generation, pure-Cu2O resulted in the highest HCOH production (419 mu mol g(-1) h(-1)) with a low amount of CH3OH generated (11 mu mol g(-1) h(-1)). After supported Cu2O in DA, CH3OH generation (38 mu mol g(-1) h(-1)) was favored up to 3.4 times. The selectivity for CH3OH generation was correlated to a more efficient charge transfer and the formation of unidentate carbonate species on Cu/DA sample, which was demonstrated by PL and FTIR analysis, respectively.