CuO coatings on glass fibers: a hybrid material for CO_2 adsorption and photocatalytic reduction to solar fuels

摘要

The CO_2 capture and its photocatalytic conversion (CCPC) to solar fuels is one promising route to fighting global warming. The CCPC process implies the use of CO_2, solar light, and materials to produce solar fuels of low carbon content. The materials must fulfill with the double function of capture and photocatalytic convert of the CO_2 into solar fuels. For this purpose, copper oxide (CuO) is an excellent candidate to act as both: adsorbent and photocatalyst. Scaling-up the CCPC process requires the immobilization of CuO on commercially available substrates such as glass fibers, which offers a homogeneous surface exposure, efficient absorption of solar energy, and an easy application in reactors. In this work, the fabrication of CuO coatings on glass fibers by a simple microwave-hydrothermal method to produce solar fuels (CH_3OH and HCOH) in CCPC process is proposed. Three glass fibers with different chemical compositions and slit (open area) were selected as supports. The best efficiency for CO_2 capture (3080 mg_(CO2) g~(-1)) was obtained with the CuO coating deposited in a substrate rich in Na_2O and CaO. Once the CO_2 was adsorbed, the coatings were exposed to visible LED light to carry out its conversion to solar fuels (CH_3OH and HCOH). According to the results, both high CuO content and high slits in the fibers promoted an increase in the CO_2 conversion to HCOH (2.7 nmol cm~(-2) h~(-1)) and CH_3OH (37.6 nmol h~(-1) cm~(-2)). The presence of Na_2O in the substrates played an essential role as a hole scavenger in the photocatalytic CO_2 reduction, preventing the re-oxidation of the products. The use of glass fibers as support of CuO promoted efficiencies up to 11 times higher than other materials used in CCPC process.