C-H Shin, H-Y Lee, F.K. Tareq, J-S Yu
Deagu Gyeongbuk Institute of Science and Technology,
Korea
Keywords: highly graphitized carbon, catalyst support, Rh nanoparticles, hydrogen evolution reaction, water electrolyzer
Summary:
State-of-the-art electrocatalyst is based on catalytically active metal deposited on conductive porous carbon. Herein, we report a new strategy of engineering of a honeycomb-structured S and N dual-doped graphene-like carbon (SNG) as a supporting material for Rh catalysts by a simple low-temperature (850 oC) pyrolysis of S-doped carbon nitride (S-CN) as a single precursor for C, N and with Mg. Interestingly, here Mg plays a marvelous dual role not only as a reducing agent for graphitizing the S-CN but also as a precursor for new Mg3N2 and MgS products, which play as pore-generating templates for honeycomb-like structure. The Rh/SNG catalyst (5.2 wt.%) outperforms state-of-the-art commercial Pt/C for hydrogen evolution reaction (HER) under alkaline settings with an extremely lower overpotential of 13 mV at 10 mA cm-2, a lower Tafel value, and a higher turnover frequency. In addition to its superior catalytic activity, it also demonstrates long-term durability (500 h) with negligible decay. The distinctive properties of SNG, including S and N dual doping, high crystallinity, superior electrical conductivity, and highly porous honeycomb structure, are credited with this remarkable HER performance. The S and N dopants in the SNG framework optimize the electronic structure of the Rh as illustrated by first-principal density functional theory calculations and electronic structure analysis. The creation of SNG as a support to anchor active components using this innovative technique will open up new possibilities for creating benchmark electrocatalysts for different electrochemical systems.