Quantum dots exhibit great potential in photocatalytic CO2 conversion into value-added fuels to achieve a carbon-neutral society, owing to their unique optical properties and tunable surface chemistry. However, the generation of multi-carbon hydrocarbon products remains a grand challenge. Herein, polyethyleneimine (PEI) coated AgInS2 quantum dots (AgInS2@PEI QDs) are designed for the photo-catalytic conversion of CO2 to C2 products. It is found that the yield and selectivity of C2H6 can be significantly enhanced by regulating the content of Ag and PEI in AgInS2@PEI QDs. Under the optimal conditions, C2H6 yield reaches 63 μmol g-1, and the electron selectivity is 30.3 %. A mechanistic study reveals that PEI effectively promotes the accumulation of photogenerated electrons, and the CO-enriched local environment caused by Ag boosts CC coupling on asymmetric bimetallic sites. This work offers new insight on the design of efficient quantum dot photocatalysts for CO2 conversion to C2 products.

The single-use waste plastics is one of the major concerns globally to society as well as to the scientific community. It is even more so at the present-day due to the rapid production of plastic and polymeric materials to meet the societal demand. The consumers’ demand and dependency on plastic is huge due to its versatility, low production cost, light weight and numerous applications of it. With increasing the demand, waste plastic generation is also high that leads to creation of environmental and health problems like vomiting, anemia, headache, kidney, liver damage, cancer, shortened lifespan and chronic damage to nervous system. Therefore, new and modern techniques such as pyrolysis has been developed to reduce the environmental pollution and cutting of carbon tracers of plastic products by reducing the emissions of oxides of carbon like monoxide (CO) and carbon dioxide (CO2) as compared to other technologies. This review paper mainly focused on the plastic waste generation scenario in India and minimization technique to produce fuels. Additionally, other new technologies to handle waste plastic along with energy generation (in the form of oil and gas production) with the specific process parameters (reaction time, reactor type, catalyst type and reaction temperature) to obtain the maximum yield are also discussed. The technoeconomic analysis and energy participation of waste plastic oil has also been highlighted to enhance the utilization of pyrolysis products and their futuristic application as an automotive fuel. An attempt was also made to analyze the emissions reduction as well as promotion of circular economy.

In this work, the carbon dioxide capture of waste derived chars was investigated. The char samples were obtained by pyrolysis of municipal plastic waste, biomass and sewage sludge from agriculture at 400, 600 and 900 °C in nitrogen atmosphere. For further experiments, chars with a grain size between 0.315 mm and 1.50 mm were investigated. The CO2 uptake capacity of samples was tested at 40 °C through a 10 adsorption-desorption cycles using a mixture of 70 % nitrogen and 30 % carbon dioxide. The CO2 uptake capacity of the reference activated carbon was 3.71–3.90 mmol CO2/g, while that of the waste derived char samples varied between 0.76–2.33 mmol CO2/g depending on the pyrolysis temperature and the raw materials. Chars with large specific surface area obtained at 900 °C had the highest CO2 uptake capacity. Char obtained from municipal plastic waste at a pyrolysis temperature of 900 °C has the largest specific surface area. The biomass and sewage sludge derived chars contained alkali metals and earth metals in oxide form, therefore the possibility of their application for carbonization-calcination cycles was also investigated. In case of the high-temperature tests, the CO2 uptake took place at 750 °C, while the release at 900 °C. During the 10 cycles test, significant decrease in capacity up to the 5th cycle was found. The capacity of char obtained from agricultural sewage sludge was 18.68 mmol CO2/g in the first cycle, which decreased drastically to 2.88–2.96 mmol CO2/g after the 5th cycle.