Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Abstract

Density functional theory (DFT) was employed to investigate the hydrogen evolution reaction (HER) on pristine and nitrogen doped carbon nanotubes (CNTs) in acidic solution. As the reaction is an electrocatalytic surface reaction, an accurate description of HER requires performing simulations under constant electrode potential conditions. To this end, we examined HER at several electrode charges allowing us to determine grand canonical activation energies as a continuous function of electrode potential. By studying the elementary steps of HER -the Volmer, Tafel and Heyrovsky reactions -and by considering hydrogen coverage effects, we found that the Volmer-Heyrovsky mechanism is the predominant HER mechanism on CNTs with the Heyrovsky step being rate-determining. Our results indicated that CNTs are electrochemically active towards HER, which seen as a decrease in activation energies with growing electrode potential, but that the activity is lower than on platinum matching experimental data.Substitutional nitrogen doping did not improve HER activity, and further research is required to determine which nitrogen configurations contribute to the enhanced catalytic activity observed for experimental NCNTs.

Theoretical Insight into the Hydrogen Evolution Activity of Open-Ended Carbon Nanotubes

“…14 By contrast, the number of studies [15][16][17][18] exploring HER on carbonbased materials remains scarce and there is no theory motivated consensus on, for example, which dopants contribute to HER activity. In this Letter, we consider pristine open-ended CNTs and demonstrate how the reactivity of carbon can be tuned by the formation of 5-ring structures.…”

Revisiting the Volmer–Heyrovský mechanism of hydrogen evolution on a nitrogen doped carbon nanotube: constrained molecular dynamics versus the nudged elastic band method

“…Instead, the kinetics of these within electrochemical energy conversion highly relevant reactions have been investigated atomistically employing only static approaches. [27][28][29][30][31][32][33][34][35] This work presents a comparative study of the CI-NEB and constrained MD methodologies and their ability to describe the transition path and the associated potential energy surface of the Volmer-Heyrovský mechanism of HER. In acidic media, the Volmer-Heyrovský mechanism proceeds via two protoncoupled electron transfer (PCET) steps; (1) electrosorption of a solvated proton, i.e.…”

Synthesis of Si‐Doped CNT and Its Catalytic Ability in Hydrogen Evolution Reaction

“…In addition, several experiments were performed to show the effects of the silicon precursor's amount, the order of introducing precursors and the effect of growth's temperature on the yields, structure and morphology of the product. Moreover, density functional theory calculations showed the catalytic potency for CNTs in the hydrogen evolution reaction (HER) . The reported studies showed that these materials could decrease the barriers and increase the potential (V) of this reaction when they employed as catalyst ,.…”

“…Moreover, density functional theory calculations showed the catalytic potency for CNTs in the hydrogen evolution reaction (HER). [19] The reported studies showed that these materials could decrease the barriers and increase the potential (V) of this reaction when they employed as catalyst. [20,21] In the published experimental study, the electrochemical behavior of CNTs as a catalyst of HER has been investigated.…”