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Mechanism investigation of enhanced electrochemical H2O2 production performance on oxygen-rich hollow porous carbon spheres
Nano Research 2022, 15 (5): 4599-4605
Published: 02 February 2022
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Electrochemical oxygen reduction is a promising approach for the sustainable decentralized production of H2O2, but its viable commercialization is hindered by the insufficient development of efficient electrocatalysts. Here, we demonstrate a promising carbon-based catalyst, consisting of oxygen-rich hollow mesoporous carbon spheres (HMCSs), for selective oxygen reduction to H2O2. The as-prepared HMCS exhibits high onset potential (0.82 V) and half-wave potential (0.76 V), delivering a significant positive shift compared with its oxygen-scarce counterparts and commercial Vulcan carbon. Moreover, excellent H2O2 selectivity (above 95%) and electrochemical stability (7% attenuation after 10 h operation) make this material a state-of-the-art catalyst for electrochemical H2O2 production. The outstanding performance arises from a combination of several aspects, such as porous structure-facilitation of mass transport, large surface area, and proper distribution of oxygen-containing functional groups modification on the surface. Furthermore, the proposed oxygen reduction reaction (ORR) mechanism on HMCS surface reveals that –OH functional groups help promote the first electron transfer process while other oxygen modification facilitate the second electron transfer.

Research Article Issue
Bimetallic metal-organic framework derived doped carbon nanostructures as high-performance electrocatalyst towards oxygen reactions
Nano Research 2021, 14 (5): 1533-1540
Published: 23 November 2020
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Downloads:37

Rational design and development of cost-effective, highly active and durable bifunctional electrocatalysts towards oxygen redox reactions is of critical importance but great challenge for the broad implementation of next-generation metal-air batteries for electric transportation. Herein, a high-performance electrocatalyst of cobalt and zinc sulfides nanocrystals embedded within nitrogen and sulfur co-doped porous carbon is successfully designed and derived from bimetallic metal-organic frameworks of cobalt and zinc containing zeolitic imidazolate frameworks. The unique nanostructure contains abundant electrocatalytic active sites of sulfides nanocrystals and nitrogen and sulfur dopants which can be fast accessed through highly porous structure originate from both zinc vaporization and sulfurization processes. Such bifunctional electrocatalyst delivers a superior half-wave potential of 0.86 V towards oxygen reduction reaction and overpotential of 350 mV towards oxygen evolution reaction, as well as excellent durability owing to the highly stable carbon framework with a great graphitized portion. The performance boosting is mainly attributed to the unique nanostructure where bimetallic cobalt and zinc provide synergistic effect during both synthesis and catalysis processes. The design and realization pave a new way of development and understanding of bifunctional electrocatalyst towards clean electrochemical energy technologies.

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