Abstract:environment each year, an emblem of our increasingly unsustainable economic system in which materials and energy are produced, used and promptly discarded. Photoreforming is a sunlight-driven technology that can help disrupt this linear model by simultaneously reclaiming the value in waste and contributing to renewable hydrogen production. This Review examines the advantages and challenges of photoreforming of real waste streams. By reviewing literature on photoreforming and conducting basic techno-economic an… Show more
“…The base inaccessible polyolefins can be removed from the hydrolysate during the pre-treatment by simple filtration (Supplementary Fig. 27a ) 16 . Then, the lactate and glycerol from digested PLA and lipids can also be transformed to acetate and formate, respectively (Supplementary Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The ethylene glycol (EG) component of PET is readily oxidized by photogenerated holes which improves H 2 production rate from water. Despite the well-established methodology, the process still suffers from low spatial productivity and poor selectivity towards a single high-value oxidation product (Supplementary Table 1 ) 16 , 17 . Fig.…”
Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H2 fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm−2). A nickel-modified cobalt phosphide (CoNi0.25P) electrocatalyst is developed to achieve a current density of 500 mA cm−2 at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi0.25P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products.
“…The base inaccessible polyolefins can be removed from the hydrolysate during the pre-treatment by simple filtration (Supplementary Fig. 27a ) 16 . Then, the lactate and glycerol from digested PLA and lipids can also be transformed to acetate and formate, respectively (Supplementary Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The ethylene glycol (EG) component of PET is readily oxidized by photogenerated holes which improves H 2 production rate from water. Despite the well-established methodology, the process still suffers from low spatial productivity and poor selectivity towards a single high-value oxidation product (Supplementary Table 1 ) 16 , 17 . Fig.…”
Plastic wastes represent a largely untapped resource for manufacturing chemicals and fuels, particularly considering their environmental and biological threats. Here we report electrocatalytic upcycling of polyethylene terephthalate (PET) plastic to valuable commodity chemicals (potassium diformate and terephthalic acid) and H2 fuel. Preliminary techno-economic analysis suggests the profitability of this process when the ethylene glycol (EG) component of PET is selectively electrooxidized to formate (>80% selectivity) at high current density (>100 mA cm−2). A nickel-modified cobalt phosphide (CoNi0.25P) electrocatalyst is developed to achieve a current density of 500 mA cm−2 at 1.8 V in a membrane-electrode assembly reactor with >80% of Faradaic efficiency and selectivity to formate. Detailed characterizations reveal the in-situ evolution of CoNi0.25P catalyst into a low-crystalline metal oxy(hydroxide) as an active state during EG oxidation, which might be responsible for its advantageous performances. This work demonstrates a sustainable way to implement waste PET upcycling to value-added products.
“…Future work should build upon this proof-of-concept PR panel system by developing more active photocatalysts, enhancing sheet stability, improving waste solubility, and pursuing further up-scaling. [34]…”
Solar-driven reforming uses sunlight and a photocatalyst to generate H 2 fuel from waste at ambient temperature and pressure. However, it faces practical scaling challenges such as photocatalyst dispersion and recyclability, competing light absorption by the waste solution, slow reaction rates and low conversion yields. Here, the immobilisation of a noble-metalfree carbon nitride/nickel phosphide (CN x j Ni 2 P) photocatalyst on textured glass is shown to overcome several of these limitations. The 1 cm 2 CN x j Ni 2 P panels photoreform plastic, biomass, food and mixed waste into H 2 and organic molecules with rates comparable to those of photocatalyst slurries. Furthermore, the panels enable facile photocatalyst recycling and novel photoreactor configurations that prevent parasitic light absorption, thereby promoting H 2 production from turbid waste solutions. Scalability is further verified by preparing 25 cm 2 CN x j Ni 2 P panels for use in a custom-designed flow reactor to generate up to 21 μmol H 2 m À 2 h À 1 under "real-world" (seawater, low sunlight) conditions. The application of inexpensive and readily scalable CN x j Ni 2 P panels to photoreforming of a variety of real waste streams provides a crucial step towards the practical deployment of this technology.
“…These upcycling technologies should be encouraged and implemented by governments in their waste management programs. Renewable energy, such as low- or medium-grade solar thermal power, should be used to upcycle plastic waste to obtain hydrogen fuel and produce clean carbon 9 . With concerted efforts from industries, and financial and policy support from governments, these novel technologies could be upscaled for commercial applications alongside the push to achieve net-zero emissions in the coming decades.…”
The COVID-19 pandemic is exacerbating plastic pollution. A shift in waste management practices is thus urgently needed to close the plastic loop, requiring governments, researchers and industries working towards intelligent design and sustainable upcycling.
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