The Role of Transition Metal and Nitrogen in Metal–N–C Composites for Hydrogen Evolution Reaction at Universal pHs

Abstract

For the first time, we demonstrated that transition metal and nitrogen codoped carbon nanocomposites synthesized by pyrolysis and heat treatment showed excellent catalytic activity toward hydrogen evolution reaction (HER) in both acidic and alkaline media. The overpotential at 10 mA cm–2 was 235 mV in a 0.5 M H2SO4 solution at a catalyst loading of 0.765 mg cm–2 for Co–N–C. In a 1 M KOH solution, the overpotential was only slightly increased by 35 mV. The high activity and excellent durability (negligible loss after 1000 cycles in both acidic and alkaline media) make this carbon-based catalyst a promising alternative to noble metals for HER. Electrochemical and density functional theory (DFT) calculation results suggested that transition metals and nitrogen played a critical role in activity enhancement. The active sites for HER might be associated with metal/N/C moieties, which have been also proposed as reaction centers for oxygen reduction reaction.

Rational Design of Graphene‐Supported Single Atom Catalysts for Hydrogen Evolution Reaction

“…We found that Pd‐SAC and Ni‐SAC had very weak interactions with hydrogen as their Gibbs free energy is very high (Δ G H * = 1.86 and 1.62 eV, respectively) while Re‐SAC, Mo‐SAC, Ti‐SAC, W‐SAC, and Ta‐SAC exhibited very high negative Gibbs free energy (−0.92, −0.93, −0.94, −1.44, and −1.64 eV, respectively) indicating strong attraction for hydrogen. As in case of SACs, the active site (metal) lies on the surface (nonedge side) of graphene, therefore, we proposed the HER mechanism by considering Volmer–Heyrovsky pathways (Figure S2, Supporting Information) rather than the Volmer–Tafel pathways designed for edge side hydrogen adsorption …”

Strategies to improve electrocatalytic and photocatalytic performance of two-dimensional materials for hydrogen evolution reaction

“…Doping with non-metallic N atoms can induce graphitization and activate transition metals [374]. Le and coworkers [375] investigated the influence of N-doping on the modification of Ti3AlC2. A simple synthesis method was used to prepare N-Ti3AlC2 (Fig.…”

“…The structure-activity relationship showed that the introduction of N species changed the electronic density of the original oxygen species, making Ti-N more effective in the HER ( Fig. 35(d)-(f)) [375].…”

Defect Engineering of Molybdenum-Based Materials for Electrocatalysis

“…In recent years, the increasing energy and environmental issues have prompted extensive research towards renewable, green, and sustainable energy saving, storage, and conversion systems [1,2]. Some of the prominent ones include water electrolytic technology [3], metal-air batteries [4,5], fuel cells [6], and ammonia synthesizing, involving crucial electrochemical reactions such as oxygen reduction/evolution, hydrogen oxidation/evolution, and the nitrogen reduction.…”