Recent Advances in Waste Plastic Transformation into Valuable Platinum‐Group Metal‐Free Electrocatalysts for Oxygen Reduction Reaction

Abstract

Plastic waste causes severe environmental hazards, owing to inadequate disposal and limited recycling. Under the framework of circular economy, there are urgent demands to valorize plastic waste more safely and sustainably. Therefore, much scientific interest has been witnessed recently in plastic waste‐derived electrocatalysts for the oxygen reduction reaction (ORR), where the plastic waste acts as a cost‐effective and easily available precursor for the carbon backbone. The ORR is not only a key efficiency indicator for fuel cells and metal–air batteries but also a major obstacle for their commercial realization. The applicability of the aforementioned electrochemical devices is limited, owing to sluggish ORR activity and expensive platinum‐group metal electrocatalysts. However, waste‐derived ORR electrocatalysts are emerging as a potential substitute that could be inexpensively fabricated upon the conversion of plastic waste into active materials containing earth‐abundant transition metals. In this Minireview, very recent research developments regarding plastic waste‐derived ORR electrocatalysts are critically summarized with a prime focus on the followed synthesis routes, physicochemical properties of the derived electrocatalysts, and their ultimate electrochemical performance. Finally, the prospects for the future development of plastic waste‐derived electrocatalysts are discussed.

Valorization of the inedible pistachio shells into nanoscale transition metal and nitrogen codoped carbon-based electrocatalysts for hydrogen evolution reaction and oxygen reduction reaction

“…Fabrication of such carbonbased electrocatalysts can be further economized using waste biomasses as readily available and cost-effective carbon sources [28]. Carbon recovery from waste products itself is an important research topic within the core of circular economy where derived carbon-based nanomaterials could find their diverse application in the arena of energy conversion and storage [29][30][31][32]. It is an astonishing fact that annually more than 140 billion metric tons of biomass are gathered all over the world in the form of agricultural waste [33].…”

Mechanochemistry Milling of Waste Poly(Ethylene Terephthalate) into Metal–Organic Frameworks

“…Mechanical recycling usually leads to low‐quality products [8] . In contrast, chemical upcycling, which can convert plastic wastes into high‐quality monomers/oligomers or high‐value chemical products, has drawn great attention for the sustainability and profitability [9–14] . For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others [15–18] .…”

“…[8] In contrast, chemical upcycling, which can convert plastic wastes into high-quality monomers/oligomers or high-value chemical products, has drawn great attention for the sustainability and profitability. [9][10][11][12][13][14] For example, chemical upcycling of PET is being extensively investigated to produce valuable chemicals, materials, and fuels by hydrolysis, solvolysis, hydrogenolysis, pyrolysis, and others. [15][16][17][18] Kratish et al employed a carbon-supported single-site molybdenum-dioxo catalyst to selectively depolymerize PET into H 2 BDC and ethylene under 1 bar H 2 atmosphere at 260 °C.…”

Waste Face Surgical Mask Transformation into Crude Oil and Nanostructured Electrocatalysts for Fuel Cells and Electrolyzers

“…[ 46 , 48 , 49 ] Recently, also waste plastics were transformed into carbonaceous and PGM‐free electrocatalysts. [ 45 , 50 , 51 , 52 ]…”