Rationalizing the Hydrogen and Oxygen Evolution Reaction Activity of Two-Dimensional Hydrogenated Silicene and Germanene

Abstract

We have undertaken first-principles electronic structure calculations to show that the chemical functionalization of two-dimensional hydrogenated silicene (silicane) and germanene (germanane) can become a powerful tool to increase the photocatalytic water-splitting activity. Spin-polarized density functional theory within the GGA-PBE and HSE06 types of exchange correlation functionals has been used to obtain the structural, electronic, and optical properties of silicane and germanane functionalized with a series of nonmetals (N, P, and S), alkali metals (Li, Na, and K) and alkaline-earth metals (Mg and Ca). The surface-adsorbate interaction between the functionalized systems with H2 and O2 molecules that leads to envisaged hydrogen and oxygen evolution reaction activity has been determined.

Adsorption Energetics of Atoms and Diatomic Gases with Electrocatalysis Approach towards Hydrogen and Oxygen Evolution Reaction on Pt Surfaces

“…Where, E [surface + H] , E [surface] and denote the total energy after the hydrogen adsorbed on the platinum surface, the total energy of a clean platinum surface and the total energy of an H 2 in the gas phase, respectively. The same approach can be applied to calculate the ΔE ZPE and its value can differ from 0.01 to 0.04 eV ,. The third term in the equation (2)indicates the entropy difference of hydrogen in adsorbed and H 2 gas phase state and is obtained by,…”

“…The same approach can be applied to calculate the ΔE ZPE and its value can differ from 0.01 to 0.04 eV. [43,[57][58] The third term in the equation (2)indicates the entropy difference of hydrogen in adsorbed and H 2 gas phase state and is obtained by,…”

Theoretical Evidence behind Bifunctional Catalytic Activity in Pristine and Functionalized Al2C Monolayers

“…The free energy of the adsorbed hydrogen is defined as DG H* ¼ E ads þ DE ZPE À TDS H (H* is the adsorbed phase of hydrogen on the surface), where E ads is the adsorption energy of hydrogen and DE ZPE is the zero point energy (ZPE) difference of H 2 in adsorbed and gas state, which is around 0.04 eV. [23][24][25] The entropic contribution differencef or the adsorbed hydrogen is the third term of the equation,w hichgives rise to ac orrection value of 0.2 eV under the experimental conditions. The adsorption entropy DS H %À 1 2 DS 0 H assuming the vibrational entropy is small in the adsorbed state with DS 0 H is the entropy of H 2 in gas phase.T he free energy corresponding to the adsorp- Table 1.…”

“…There is another assumption based on the chemisorption tendency of the corresponding surface. [23] There is also aconcept to actually determine the overpotential of OER, that undergoes af our electron pathway with three different adsorbates O*, OH* and OOH* (* = adsorbed). One can predict ag ood OER based on the lower overpotential value, that can be evaluated from the differenceo ft he adsorption freee nergies that are constructing the reaction coordinate.…”

TiS2 Monolayer as an Emerging Ultrathin Bifunctional Catalyst: Influence of Defects and Functionalization

“…[2][3][4][5] There are several methods to produce hydrogen in the laboratory, among which photo-catalytic water splitting has become the most promising and environmental friendly approach. [6][7][8][9] The complete water splitting process can be divided into two half reactions. The reduction half reaction i. e. hydrogen evolution reaction (HER) generally takes place in the cathode, while the oxidation half reaction i. e. oxygen evolution reaction (OER) takes place in the anode.…”