Anthraquinone-modified Carbon-based Catalyst And Its Electrocatalytic Oxygen Reduction To Produce Hydrogen Peroxid

As one of the most important and indispensable agents,hydrogen peroxide（H₂O₂）has gained increasing attention in daily life and various chemical industrial process,including chemical production,paper recycling,wastewater treatment.Currently,the majority of H₂O₂ production is achieved by the industrial anthraquinone oxidation process,which is cost-intensive and needs tedious extraction to produce high-purity H₂O₂.Furthermore,the centralized production poses extra costs and safety issues for transport and storage of H₂O₂.Thus,it is critical to develop alternative technologies to synthesize H₂O₂ in an eco-friendly and sustainable manner.In this respect,electrocatalytic oxygen reduction reaction（ORR）through a selective 2 electron pathway emerges as a fascinating route that enables portable,on-demand and decentralized synthesis of H₂O₂.Moreover,the production cost can be further reduced in combination with renewable energy sources.Nowadays,great efforts have been made to explore cost-effective and high-performance electrocatalysts.Noble metals and their alloys have shown great promise as 2 e^-ORR electrocatalysts,but the low abundance and high cost impede their commercial deployment on a large scale.Alternatively,metal-free carbon-based materials have the great merit of low cost,good electrical conductivity,excellent stability,and ease of modification,making them particularly appealing as cost-effective electrocatalysts for 2 e^-ORR.Nevertheless,previous studies have demonstrated that the pristine carbon materials exhibit relatively low activity and selectivity,and thus structural and compositional regulation are urgently needed to boost their electrocatalytic performance.Standing from the perspective of surface modification of non-metallic carbon materials,and taking the improvement the activity and selectivity of ORR reaction to generate H₂O₂ as the target,the following studies are conducted:（1）The porous carbon substrates were prepared by the sodium chloride-assited template method,and anthraquinone monomers rich in active sites were polymerized to the surface of the porous carbon substrates by organic polymerization.The rich porous structure is conducive to the loading of the rich active sites and the full contact with the electrolyte.Electrochemical tests showed that the composite could effectively enhance the electrocatalytic activity and selectivity towards 2 e^-ORR.The selectivity of the composite formed at 0.5 V（vs.RHE）was increased by nearly 20%compared with that of the porous carbon material,and the composite could maintain stability for 15 h.（2）Using carbon nanotube as the conductive substrate,the anthraquinone monomers were in situ polymerized and deposited.During the synthesis process,the polymerized products are deposited on the surface of CNT throughπ-π*interactions,resulting in the formation of polysulfide anthraquinone/carbon nanotube（PAQS/CNT）composite materials.CNT is beneficial to enhance the electrical conductivity of the composite and thus accelerate the reaction kinetics.In the meantime,the open network structure ensures the efficient contact between active components and the electrolyte.As a result,the in situ formed poly（anthraquinonyl sulfide）/carbon nanotube（PAQS/CNT）composites,serving as the superior electrocatalysts,could effectively enhance the electrocatalytic activity and selectivity towards 2 e^-ORR.Importantly,the quinone-containing composite shows excellent electrochemical HO₂^-production with high selectivity（～91%）and stability（over20 h）at 0.5 V（vs.RHE）.Moreover,acid leaching experiments were performed,further evidencing the quinone-based active sites of PAQS/CNT（C=O）.