Graphene oxide-polydopamine derived N, S-codoped carbon nanosheets as superior bifunctional electrocatalysts for oxygen reduction and evolution

Engineering carbon materials as the bifunctional catalysts for both electrocatalytic oxygen reduction/evolution reactions (ORR/OER) is highly promising for the large-scale commercialization of regenerative fuel cells and rechargeable metal-air batteries. Codoping carbons with heteroatoms can achieve unique electronic structures and show tailored electrocatalytic capabilities by rationally regulating their dopants. Sulfur is one of the most important dopants from both experimental and theoretical perspectives. In this work, a novel, highly efficient and environmentally benign method for sulfur incorporation into carbon framework has been developed facilely on the basis of graphene oxide-polydopamine (GD) hybrids to derive the N, S-codoped mesoporous carbon nanosheets. 16.7 at% S can be conjugated to the GD hybrids associated with the S doping efficiency up to 6.1% after 800 degrees C pyrolysis, which is higher than most previous S doping approaches. The resultant N, S-codoped mesoporous carbon nanosheets exhibit superior performance with favorable kinetics and excellent durability as a bifunctional ORR and OER catalyst, which is much better than that of most reported metal-free doped carbon, even transition metal and noble metal catalysts. The high concentrations of multiple dopants, abundant porous architecture and good electron transfer ability are believed to significantly expedite the ORR and OER catalytic processes. In the light of physicochemical versatility and structural tunability of polydopamine (PDA), this work provides a universal platform towards further development of PDA-based carbon materials with heteroatom dopants as the highly efficient electrocatalysts. (C) 2015 Elsevier Ltd. All rights reserved.