Transition Metal and N Doping on AlP Monolayers for Bifunctional Oxygen Electrocatalysts: Density Functional Theory Study Assisted by Machine Learning Description

Abstract

It is vital to search for highly efficient bifunctional oxygen evolution/reduction reaction (OER/ORR) electrocatalysts for sustainable and renewable clean energy. Herein, we propose a single transition-metal (TM)-based defective AlP system to validate bifunctional oxygen electrocatalysis by using the density functional theory (DFT) method. We found that the catalytic activity is enhanced by substituting two P atoms with two N atoms in the Al vacancy of the TM-anchored AlP monolayer. Specifically, the overpotential of OER(ORR) in Co-and Ni-based defective AlP systems is found to be 0.38 (0.25 V) and 0.23 V (0.39 V), respectively, showing excellent bifunctional catalytic performance. The results are further presented by establishing the volcano plots and contour maps according to the scaling relation of the Gibbs free-energy change of *OH, *O, and *OOH intermediates. The d-band center and the product of the number of d-orbital electrons and electronegativity of the TM atom are the ideal descriptors for this system. To investigate the activity origin of the OER/ORR process, we performed the machine learning (ML) algorithm. The result indicates that the number of TM-d electrons (N e ), the radius of TM atoms (r d ), and the charge transfer of TM atoms (Q e ) are the three primary descriptors characterizing the adsorption behavior. Our results can provide a theoretical guidance for designing highly efficient bifunctional electrocatalysts and pave a way for the DFT−ML hybrid method in catalysis research.

Strain engineering in single-atom catalysts: GaPS4 for bifunctional oxygen reduction and evolution

“…To enhance the catalytic activity, doping transition metal atoms into 2D materials have been widely used in electrocatalysis. [21][22][23][24] Moreover, physical and chemical properties of the 2D materials, such as d-band structure, adsorption energy, and catalytic activity, can be modulated by strain engineering, [25][26][27][28] triggering high catalytic action. For instance, strained NiFe-MOFs with 6% lattice expansion exhibit superior catalytic performance for the OER under alkaline conditions.…”

Strain-mediated oxygen evolution reaction on magnetic two-dimensional monolayers

“…In the OER, the PDS is an important reaction step that dominates the overall catalytic performance of catalysts, 47 which can be obtained from DG max i .…”

“…For each elementary reaction step, the Gibbs free energy difference Δ G i ( i = 1, 2, 3, 4) is given by these equations: 45,46 where the value of 4.92 eV is the total change in the Gibbs free energy for the overall reaction 2H 2 O → O 2 + 2H 2 at 298.15 K. After that, the theoretical overpotential η for the OER is obtained using: 45 Δ G max i = max[Δ G 1 ,Δ G 2 ,Δ G 3 ,Δ G 4 ] η = Δ G max i / e − 1.23In the OER, the PDS is an important reaction step that dominates the overall catalytic performance of catalysts, 47 which can be obtained from Δ G max i .…”

The surface reconstruction induced enhancement of the oxygen evolution reaction on α-SnWO4 (010) based on a density functional theory study

“…9a, demonstrating that the OER is an exothermic process when the potential surpasses 3.57 V. Moreover, the overpotential value for the OER of O-W termination is 2.34 V. It should be noted that this value is higher than that of the other photocatalysts. 62 For ST3 termination, the OER results are shown in Fig. S8 (ESI †).…”