Yeddala Munaiah, Thakur Pallavi, A Anugraha, Narayanan Tharangattu N
Tata Institute of Fundamental Research - Hyderabad, Sy. No. 36/P, Gopanapally Village, Serilingampally Mandal, Hyderabad 500107, India.
Beilstein J Nanotechnol. 2020 Mar 9;11:432-442. doi: 10.3762/bjnano.11.34. eCollection 2020.
On-site peroxide generation via electrochemical reduction is gaining tremendous attention due to its importance in many fields, including water treatment technologies. Oxidized graphitic carbon-based materials have been recently proposed as an alternative to metal-based catalysts in the electrochemical oxygen reduction reaction (ORR), and in this work we unravel the role of C=O groups in graphene towards sustainable peroxide formation. We demonstrate a versatile single-step electrochemical exfoliation of graphite to graphene with a controllable degree of oxygen functionalities and thickness, leading to the formation of large quantities of functionalized graphene with tunable rate parameters, such as the rate constant and exchange current density. Higher oxygen-containing exfoliated graphene is known to undergo a two-electron reduction path in ORR having an efficiency of about 80 ± 2% even at high overpotential. Bulk production of HO via electrolysis was also demonstrated at low potential (0.358 mV vs RHE), yielding ≈34 mg/L peroxide with highly functionalized (≈23 atom %) graphene and ≈16 g/L with low functionalized (≈13 atom %) graphene, which is on par with the peroxide production using state-of-the-art precious-metal-based catalysts. Hence this method opens a new scheme for the single-step large-scale production of functionalized carbon-based catalysts (yield ≈45% by weight) that have varying functionalities and can deliver peroxide via the electrochemical ORR process.
通过电化学还原进行现场过氧化物生成因其在包括水处理技术在内的许多领域的重要性而备受关注。氧化石墨基材料最近被提议作为电化学氧还原反应（ORR）中金属基催化剂的替代品，在这项工作中，我们揭示了石墨烯中C=O基团对可持续过氧化物形成的作用。我们展示了一种将石墨一步通用电化学剥离为石墨烯的方法，其氧官能度和厚度可控，从而形成大量具有可调速率参数（如速率常数和交换电流密度）的功能化石墨烯。已知含氧量更高的剥离石墨烯在ORR中会经历双电子还原路径，即使在高过电位下效率也约为80±2%。在低电位（相对于可逆氢电极，0.358 mV）下也证明了通过电解大量生产过氧化氢，使用高度功能化（约23原子%）的石墨烯可产生约34 mg/L的过氧化物，使用低功能化（约13原子%）的石墨烯可产生约16 g/L的过氧化物，这与使用最先进的贵金属基催化剂生产过氧化物的水平相当。因此，该方法为一步大规模生产具有不同功能且可通过电化学ORR过程产生过氧化物的功能化碳基催化剂（产率约为45%重量）开辟了新方案。
