Enhanced and recyclable CO2 photoreduction into methanol over S-scheme PdO/GdFeO3 heterojunction photocatalyst under visible light

Abstract

Photocatalytic conversion of carbon dioxide (CO2) into value-added chemicals over ceramic photocatalysts has presently regarded as an eco-friendly and workable approach for saving energy resources and reducing global warming. Accordingly, marvellous research is being performed for engineering enhanced photocatalysts. So, we present a solution-based process for the synthesis of gadolinium orthoferrite nanocrystals (GdFeO3) that are supported with trace amounts (0.5 ∼ 2.0 wt%) of palladium oxide (PdO) to form PdO/GdFeO3 nanocomposites. These synthesized nanostructures were applied for the photocatalytic conversion of carbon dioxide (CO2) into methanol (CH3OH) for the first time. Physicochemical characteristics of the synthesized materials revealed the growth of perovskite GdFeO3nanocrystals supported with tiny PdO dots. Also, a slight reduction in surface areas from 214 to 193 m2g−1 owing to the PdO inclusion. Interestingly, the visible-light absorption was greatly enhanced with a reduction of the overall bandgap down to 2.14 eV compared to 2.37 eV for the pristine GeFeO3. The photoinduced carrier recombination was also suppressed with enhanced mobility, as confirmed by photoluminescence and photocurrent studies. The tuned 2.0 gL−1 dosage of 1.5% PdO/GdFeO3 has resulted in 1550 μmol g−1 CH3OH production within 9 h of visible light illumination, which is > 7.8 times than pristine GdFeO3. Moreover, this novel nanocomposite displays sustainable recyclability of 98% after five cycles. The photocatalytic performance promotion of the 1.5% PdO/GdFeO3 is attributed to the formed heterojunction that enhanced both charge transfer and mobility as well. This work proposes the realization of stable perovskite-based nanoceramics for the production of renewable fuels.