Hierarchical Electrodes of MoS ₂ Nanoflakes Wrapped on CNTs in Wood-Derived Porous Carbon Frameworks for a High-Performance Hydrogen Evolution Reaction

Abstract

Controllable fabrication of high-performance and inexpensive heterogeneous catalysts is crucial for the electrochemical hydrogen evolution reaction (HER) and renewable energy. Wood-derived electrodes provide new opportunities. Herein, N-doped carbon nanotubes (CNTs) encapsulating metal particles are in situ generated on graphitized wood (GW)-derived porous carbon frameworks and molybdenum disulfide (MoS2) nanoflakes are dispersively anchored on CNTs, resulting in hierarchical structures as a hybrid electrode (M/CNT@MoS2@GW, M = Fe, Co, and Ni). The wood matrix hybrid electrodes with abundant microchannels and hierarchical pores could supply electrolytes for continuous reaction and boost gas diffusion. Consequently, the hybrid electrocatalyst Fe/Fe3C/CNT@MoS2@GW exhibits superior HER activity with an overpotential as low as 66.79 mV at 10 mA cm–2 in an alkaline solution. The activity of the hybrid structure is reduced only by 10.18% at 20 mA cm–2 after 48 h electrolysis, with nearly no decay after 5000 cyclic voltammetry (CV) cycles, suggesting good stability and durability. Density functional theory calculations illustrate that a thermodynamically favorable hydrogen adsorption free energy (ΔG H* ≈ 0.07 eV) promotes the catalytic reactions. The results hold great potential in the exploration of wood-derived catalysts for high-performance HER.

Rise of wood-based catalytic electrodes for large-scale hydrogen production

“…The cellulose microfibril embedded in the lignin and hemicellulose matrix has crystalline and amorphous microfibril regions. 50–52 Interestingly, wood is ionic conductive when filled with water or organic electrolytes. However, the diffusion mechanism of ions through the cell wall in natural wood has been the focus of debates.…”