Photoelectrochemical CO2-to-fuel conversion with simultaneous plastic reforming

Abstract

Solar-driven conversion of CO2 and plastics into value-added products provides a potential sustainable route towards a circular economy, but their simultaneous conversion in an integrated process is yet to be accomplished. Here, we introduce a versatile photoelectrochemical (PEC) platform for CO2 conversion which is coupled to the reforming of plastic. The perovskite-based photocathode enables the integration of different CO2 reduction catalysts such as molecular cobalt porphyrin, Cu91In9 alloy, and formate dehydrogenase, which produce CO, syngas, and formic acid, respectively. The Cu27Pd73 alloy anode selectively reforms polyethylene terephthalate (PET) plastics into glycolic acid. The overall single lightabsorber PEC system operates with the help of an internal chemical bias and under zero applied voltage. The system performs similarly to bias-free, dual-light absorber tandems and shows ~10-100 fold higher production rates than photocatalytic suspension processes. This finding demonstrates efficient CO2-to-fuel conversion coupled to plastic-to-chemical PEC conversion as a promising sustainable technology powered by sunlight.

Chloride, Bromide, and Iodide Photooxidation in Acetonitrile/Water Mixtures Using Binuclear Iridium(III) Photosensitizers

“…Society is facing an energy crisis, and novel approaches toward solar energy conversion are in dire need. − Different innovative technologies have been explored for the conversion of sunlight to useful energy sources. The storage of solar energy in chemical bonds of small molecules, so-called solar fuels , represents a highly promising avenue. − Among them, hydrogen gas (H 2 ) represents a promising target for large-scale energy storage and distribution .…”

Recent advances in plastic recycling and upgrading under mild conditions

“…One of the major obstacles is the necessity of a highly caustic alkaline pretreatment (10 M NaOH) to partially hydrolyze the polymers into monomers prior to the photoreactions. [65][66][67][68][75][76][77][78][79][80][81][82][83] Moreover, low productivity and poor selectivity toward a single high-value oxidation product are still problems. Hence, future studies in this field should focus on developing more efficient photocatalysts that can break down real-world plastics completely while generating valuable organic products selectively.…”

“…Another alternative based on homogeneous species is to employ a photo-assisted Fenton reaction to produce reactive oxygen species (ROS), which can mineralize the waste plastics. [71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87] For example, Soo and coworkers developed a novel photocatalytic route using vanadium(V)-based homogeneous photocatalysts to selectively cleave the C-C bonds of PE in a solution of acetonitrile and toluene under white light-emitting diode irradiation (Fig. 11a and b), leading to the full conversion of PE into FA and alkyl formates after only six days.…”

Electrochemical Co-Production of Ammonia and Biodegradable Polymer Monomer Glycolic Acid via the Co-Electrolysis of Nitrate Wastewater and Waste Plastic

“…Therefore, as a green and sustainable solution, the use of electrocatalytic technology to upcycle polluting waste into high value-added chemicals is reliable. For example, the electroreduction process can convert NO 3 – into nontoxic nitrogen (N 2 ) or value-added ammonia (NH 3 ) under mild operating conditions. − Notably, compared to the useless N 2 , NH 3 is largely needed as a basic raw material for various chemicals and an important carbon-free energy carrier. − Meanwhile, the traditional NH 3 synthesis relies on the Haber–Bosch (H–B) process under high temperature and pressure operating conditions, resulting in serious environmental pollution and fossil energy consumption. − On the contrary, the electrochemical nitrate reduction reaction (NO 3 RR) can achieve value-added ammonia production while treating nitrate wastewater, which is a win–win environmentally friendly process. − In addition, the application of electrochemical oxidation in PET plastic waste upcycling can realize the conversion of EG from PET hydrolysate into value-added products (e.g., formate, glycolic acid (GA)). − However, most of the previous reports have focused on the conversion of EG to formate (C1), and less on C2 products. As a biodegradable material with high mechanical strength, high biocompatibility, and rapid degradation, polyglycolic acid (PGA) plastics are widely used in biomedical fields. , Nevertheless, limited GA production and high prices have resulted in insufficient PGA production.…”