Functional materials from nature: honeycomb-like carbon nanosheets derived from silk cocoon as excellent electrocatalysts for hydrogen evolution reaction

We developed a facile method to synthesize porous and N-rich carbon materials derived from Bombyx mori silk cocoons with an activation and thermal carbonization process. The silk-derived nanosheets carbon fibers consist of a porous and multilayer structure, endowing the materials with high surface area of 349.3 m(2) g(-1) and much exposed active sites. The synthesized N-rich (4.7%) carbon materials are employed as electrocatalysts for hydrogen evolution reaction (HER) and exhibit incredible catalytic performance as well as promising electrochemical durability, which are mainly attributed to the large amount of exposed active sites, high graphitization degree and the rich nitrogen elements, especially pyridine-N and graphitic-N. Typically, the silk-derived nanosheets carbon fibers activated by KCI afford a low onset potential of -63 mV (vs. RHE), a low overpotential of 137 mV at 10 mA cm(-2) and a Tafel slope of 132 mV dec(-1). The results may offer a novel and promising method for the preparation of non-metal HER catalysts derived from abundant biomass. (C) 2016 Elsevier Ltd. All rights reserved.