Abstract
Hydrogen Evolution Reaction (HER) is an attractive technology for chemical conversion of energy. Replacement of platinum with inexpensive and stable electrocatalysts remains a major bottleneck hampering large-scale hydrogen production by using clean and renewable energy sources. Here, we report electrocatalytically active and ultra-stable Polymer-Derived Ceramics towards HER. We successfully prepared ultrathin silicon and carbon (Si–C) based ceramic systems supported on electrically conducting 2D reduced graphene oxide (rGO) nanosheets with promising HER activity by varying the nature and the composition of the ceramic with the inclusion of nitrogen, boron and oxygen. Our results suggest that oxygen-enriched Si-B-C-N/rGO composites (O-SiBCN/rGO) display the strongest catalytic activity leading to an onset potential and a Tafel slope of − 340 mV and ~ 120 mV dec−1 respectively. O-SiBCN/rGO electrodes display stability over 170 h with minimal increase of 14% of the overpotential compared to ~ 1700% for commercial platinum nanoparticles. Our study provides new insights on the performance of ceramics as affordable and robust HER catalysts calling for further exploration of the electrocatalytic activity of such unconventional materials.
Highlights
Thanks to its high energy density and environment-friendly nature, hydrogen is considered to be one of the most promising alternative energy carrier for the future[1]
Our results show that Polymer-Derived Ceramics (PDCs) are clearly Hydrogen Evolution Reaction (HER) active when supported on conducting graphene and the best HER performance is obtained in the case of O-SiBCN ceramics with an overpotential of ~ 580 mV vs. reversible hydrogen electrode (RHE) for a current density of 10 mA cm−2 and a Tafel slope of ~ 120 mV dec−1
To get further understanding of the nature of the active sites of the O-SiBCN ceramics, we investigated the effect of the crystallinity of the ceramics on the electrocatalytic activity of O-SiBCN/reduced graphene oxide (rGO) and O-silicon carbonitride (SiCN)/rGO by annealing the composites at increasing temperatures (Fig. 6a,b)
Summary
Thanks to its high energy density and environment-friendly nature, hydrogen is considered to be one of the most promising alternative energy carrier for the future[1]. We report the preparation of PDCs and graphene based composites as porous and ultra-stable electrocatalysts towards the production of hydrogen. Our results show that PDCs are clearly HER active when supported on conducting graphene and the best HER performance is obtained in the case of O-SiBCN ceramics with an overpotential of ~ 580 mV vs reversible hydrogen electrode (RHE) for a current density of 10 mA cm−2 and a Tafel slope of ~ 120 mV dec−1. By taking advantage of the mechanical properties of the PDC/graphene composite, we demonstrate a free-standing electrode for the production of hydrogen that can sustain a current of 100 mA at an overpotential of 660 mV versus RHE. Together with the high stability and durability assessment, the electrochemical investigation was carefully conducted in order to correlate the catalytic activity to the nature, the porosity, the structure and the electrical conductivity of the composites. Our work sheds light on the electrocatalytic activity of inorganic ceramics as affordable and ultra-stable electocatalysts
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