Plastics-to-syngas photocatalysed by Co–Ga2O3 nanosheets

Abstract

Plastics take hundreds of years to degrade naturally, while their chemical degradation typically requires high temperature and pressure. Here, we first utilize the solar energy to realize the sustainable and efficient plastic-to-syngas conversion with the aid of water at ambient conditions. As an example, the commercial plastic bags could be efficiently photoconverted into renewable syngas by the Co-Ga2O3 nanosheets, with the hydrogen and carbon monoxide formation rates of 647.8 and 158.3 μmol g−1 h−1. In situ characterizations and labelling experiments unveil water is photoreduced into hydrogen, while non-recyclable plastics including polyethylene bags, polypropylene boxes and polyethylene terephthalate bottles are photodegraded to carbon dioxide, which is further selectively photoreduced into carbon monoxide. In-depth investigation illustrates the efficiency of syngas production mainly depends on the carbon dioxide reduction process, and hence the photocatalysts of high carbon dioxide reduction activity should be designed to promote the efficiency of plastic-to-syngas conversion in the future. The concept for the photoreforming of non-recyclable plastics into renewable syngas helps to eradicate ‘white pollution’ and alleviate the energy crisis simultaneously.

Plastic Waste Valorization by Leveraging Multidisciplinary Catalytic Technologies

“…The produced CO 2 could be further selectively photoprocessed to give a high-energy-density fuel, acetic acid, via a C–C coupling reaction over the same photocatalyst (Figure b) . A similar strategy was also demonstrated to transform plastic waste into syngas using a Co-doped Ga 2 O 3 (Co–Ga 2 O 3 ) nanosheet photocatalyst (Figure b) . Compared with pristine Ga 2 O 3 , the introduction of Co atoms dramatically enhanced the photoadsorption ability and decreased the photoluminescence intensity.…”

“…Photochemical strategies for plastic reclamation. (a) Photoreforming (PR) of plastic via photogenerated holes. , (b) Tandem catalysis for photocatalytic plastic reclamation. , (c) Photocatalytic upcycling of plastics via radicals. − …”

“…Conventionally, CO 2 is readily generated during photocatalytic processing of plastic. To tackle this issue, Xie, Sun, and co-workers proposed an efficient tandem photocatalytic process to convert waste plastics (i.e., PE, PP, PVC) into valuable chemicals in simulated natural environments (Figure b). , Specifically, PE was first photodegraded into CO 2 via C–C cleavage with 100% selectivity by a single-unit-cell Nb 2 O 5 photocatalyst within 40 h. In the meantime, O 2 was reduced to H 2 O. The produced CO 2 could be further selectively photoprocessed to give a high-energy-density fuel, acetic acid, via a C–C coupling reaction over the same photocatalyst (Figure b) .…”

“…143 A similar strategy was also demonstrated to transform plastic waste into syngas using a Co-doped Ga 2 O 3 (Co−Ga 2 O 3 ) nanosheet photocatalyst (Figure 6b). 144 Compared with pristine Ga 2 O 3 , the introduction of Co atoms dramatically enhanced the photoadsorption ability and decreased the photoluminescence intensity. Density of states calculations indicated that Co− Ga 2 O 3 could provide more photogenerated electrons and holes.…”

Rational Design of Chemical Catalysis for Plastic Recycling

“…This key step provides a new and efficient direction for plastic upcycling. Moreover, this group further developed a photoreforming strategy to degrade waste products including PE bags, PP boxes, and PET bottles into syngas for further commercial applications . In this system, Co–Ga 2 O 3 nanosheets were used as the catalyst, the introduced H 2 O was first split into H 2 and O 2 , followed by the oxidation of plastic in the presence of O 2 to form CO 2 .…”