Supramolecular polymerization-assisted synthesis of nitrogen and sulfur dual-doped porous graphene networks from petroleum coke as efficient metal-free electrocatalysts for the oxygen reduction reaction

Abstract

Supramolecular polymerization-assisted synthesis of nitrogen and sulfur-codoped porous graphene networks (N,S-PGN) from petroleum coke as a remarkable electrocatalyst for the ORR.

Insight into the oxidative desulfurization of high-sulfur petroleum coke under mild conditions: a journey of vanadium-substituted Dawson-type phosphotungstic acid

“…Petroleum coke, a by-product from the coking of slag oil in refining, shows versatile applications in the industry based on its quality. The low-sulfur petroleum coke (S < 3.0 wt%) is mainly used to manufacture carbon products such as graphite electrodes (Wei et al 2017), activated carbon (Choi et al 2012), carbon fiber (Briceño et al 2015), graphite (Wu et al 2017). High-sulfur petroleum coke (HSPC, S > 3.0 wt%) is typically employed as fuel for heating or power, and it can only be classified as waste which causes environmental issues and needs to be handled with considerable cost (Chen and Lu 2007;Peng et al 2019;Zhong et al 2018bZhong et al , 2019.…”

Structurally Modulated Graphitic Carbon Nanofiber and Heteroatom (N,F) Engineering toward Metal-Free ORR Electrocatalysts for Polymer Electrolyte Membrane Fuel Cells

“…local H 2 -fuel starvation, high potentials applied, and throughout the start-up/shut-down series conditions . Hence, the quest is focused in search of proficient alternative ORR catalysts such as thin Pt catalysts, − non-Pt/transition metal catalysts, − and metal-free/heteroatom-doped catalysts. − Among them, heteroatom doping to various carbon nanomaterials viz. graphene, − multiwalled carbon nanotubes, − porous carbon, − carbon nanofibers, and so forth − are widely explored and found best at their ORR activity with excellent stability in both alkaline and acidic environments.…”

Nitrogen–Fluorine Dual Doped Porous Carbon Derived from Silk Cotton as Efficient Oxygen Reduction Catalyst for Polymer Electrolyte Fuel Cells

“…Oxygen reduction reaction (ORR), a cathodic reaction that decides the overall efficiency of any energy generation devices such as fuel cells and metal–air batteries, needs to be focused on extensively. , The sluggish reaction kinetics of ORR associated with strong chemical bond between two oxygen atoms (498 kJ/mol) significantly hinders the performance of the electrochemical devices . To date, platinum (Pt) and its alloy based materials have been employed as the most efficient catalysts to facilitate ORR by catalyzing O 2 into H 2 O via four-electron pathway with a lower overpotential. , Nevertheless, wide commercialization of Pt-based catalysts is greatly impeded by its high cost, lack of natural abundance, poor stability in fuel cell environment, and low tolerance to CO poisoning. , Since the past decade, exhaustive research efforts have been made to exploit the alternative low cost ORR electrocatalysts by employing either ultralow Pt loading catalysts, − transition metals based, − or metal free electrocatalysts based on heteroatom engineering principles. − Among several approaches, heteroatom doping on long-range high surface area porous carbon is attractive and obviates major limitations and mechanistic hurdles faced by metal-based catalysts. − Heteroatoms doped carbon catalysts have been found to be the best, owing to low cost, least vulnerability to methanol/CO, and efficient activity toward ORR. , The doping of heteroatoms (N, F, P, B, etc.) to the carbon materials effectively disrupts the electroneutrality of the carbon matrix and catalyzes the ORR kinetics quite similarly to precious metal catalysts. − Variation in electronic charge densities and spin densities interrupts the electroneutrality in carbon matrix and thus creates many active catalytic sites. − The maximum charge redistribution and high spin densities occur by co-doping of multiple heteroatoms with higher electronegativity deference and lead to creation of defects of many active sites that accelerate the ORR activity synergistically. − …”