NP monolayer supported transition-metal single atoms for electrochemical water splitting: a theoretical study

Computational screening of transition metal atom doped ZnS and ZnSe nanostructures as promising bifunctional oxygen electrocatalysts

The design of bifunctional oxygen electrocatalysts showing high catalytic performance for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is of great significance for developing new renewable energy storage and conversion technologies. Herein, based on the first principles calculations, we systematically explored the electrocatalytic activity of a series of transition metal atom (Fe, Co, Ni, Cu, Pd and Pt)-doped ZnS and ZnSe nanostructures for OER and ORR. The calculated results revealed that Ni- and Pt-doped ZnS and ZnSe nanostructures exhibit promising electrocatalytic performance for both OER and ORR in comparison to the pristine ZnS and ZnSe nanostructures. Especially, the OER/ORR overpotentials of Ni-doped ZnS and ZnSe nanostructures are estimated to be 0.28/0.30 and 0.31/0.31 V, respectively, disclosing their great potential as bifunctional oxygen electrocatalysts. Moreover, it is found that Ni-doped ZnS and ZnSe nanostructures for OER and ORR are on the top of the volcano plots, evincing promising catalytic performance. Our results provide theoretical insights into a feasible strategy to synthesize highly efficient ZnS- and ZnSe-based bifunctional oxygen electrocatalysts in the future.

Transition metal single-atoms supported on hexagonal ZnIn2S4 monolayers for the hydrogen evolution reaction

Herein, we report a series of 5d transition metal (TM) single atoms supported on ZIS as promising catalysts for the hydrogen evolution reaction using first-principles calculations. The binding behaviors of TMs with the ZIS surface in single-atom catalyst formation are analysed using the adsorption energy (Eads), partial density of states (PDOS), charge density difference (CDD), and crystal orbital Hamilton population (COHP). The TM@ZIS (TM = Ta, W, Re, Os, Ir, and Pt) shows excellent hydrogen evolution performance with the Gibbs free energy (ΔGH*) values from -0.120 to 0.128 eV. The Tafel and Heyrovsky reaction mechanisms to drive H2 formation are also identified.

Rational design of 2D MBene-based bifunctional OER/ORR dual-metal atom catalysts: a DFT study

Designing highly active, low-cost, and bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts is urgent for the development of metal-air batteries. Herein, by density functional theory (DFT) calculations, we systematically reported a series of dual-metal atom adsorbed novel two-dimensional (2D) MBenes as efficient bifunctional catalysts for the OER/ORR (namely 2TM/TM1TM2-Mo2B2O2, TM = Mn, Fe, Co, Ni). Our theoretical results show that 2Ni-Mo2B2O2, FeCo-Mo2B2O2 and CoNi-Mo2B2O2 exhibit outstanding OER/ORR catalytic activity with overpotentials of 0.49/0.27 V, 0.38/0.50 V and 0.25/0.51 V, respectively, exceeding those of IrO2(110) for the OER and Pt(111) for the ORR. Additionally, these highly active bifunctional catalysts can effectively suppress the hydrogen evolution reaction (HER), ensuring the absolute preference for the OER/ORR. More importantly, the Bader charge (QTM) of adsorbed dual-metal atoms is used as a descriptor of OER/ORR catalytic activity, which is linearly related to ηORR and volcanically related to -ηOER. Our work not only provides new theoretical guidance for developing noble metal-free bifunctional electrocatalysts but also enriches the application of MBenes in electrocatalysis.

Tuning coordination microenvironment of V2CTx MXene for anchoring single-atom toward efficient multifunctional electrocatalysis

The rational design of low-cost and high-performance multifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) is essential for efficient overall water splitting and rechargeable metal-air battery. Herein, through density functional theory calculations, we creatively regulate the coordination microenvironment of V₂CT_x MXene (M-v-V₂CT₂, T = O, Cl, F and S) as substrates of single-atom catalysts (SACs), and then systematically explore their HER, OER, and ORR electrocatalytic performance. Our results disclose that Rh-v-V₂CO₂ is a promising bifunctional catalyst for water splitting (overpotentials of 0.19 and 0.37 V for HER and OER). Besides, Pt-v-V₂CCl₂ and Pt-v-V₂CS₂ possess desirable bifunctional OER/ORR activity with overpotentials of 0.49/0.55 V and 0.58/0.40 V, respectively. More interestingly, Pt-v-V₂CO₂ is a promising trifunctional catalyst under vacuum, implicit and explicit solvation conditions, which transcends commercially used Pt and IrO₂ catalysts for HER/ORR and OER. The electronic structure analysis further demonstrates that surface functionalization can optimize the local microenvironment of the SACs and thus tune the interaction strength of intermediate adsorbates. This work provides a feasible strategy for developing advanced multifunctional electrocatalysts and enriches the application of MXene in energy conversion and storage.

Black phosphorene/NP heterostructure as a novel anode material for Li/Na-ion batteries

Designing heterostructured anode materials has been rendered supremely appealing to large-scale energy storage systems and storage device researchers. Recently, black phosphorene has experienced explosive development and been sought for widespread application in various domains including anode materials for electrochemistry. Hence, in this work, the black phosphorene/NP heterostructure (black P/NP) as a novel anode material for Li/Na batteries was systematically studied on the basis of first-principle calculations. Our simulations disclose that black P/NP is dynamically stable at room temperature and exhibits metallic properties. Charge density difference calculations and work function analysis demonstrate that electron charge transfer between the pristine single-layer components leads to enhanced Li/Na ion adsorption on the interlayer. To be specific, the calculated adsorption energies for Li/Na are -2.27 and -2.13 eV, respectively, which are sufficient to prevent metal aggregation during cycling. Besides, it is predicated that black P/NP has a positive and low open-circuit voltage. Excitingly, the diffusion barriers for Li and Na ions on black P/NP are 0.17 and 0.04 eV, respectively, which are superior to other typical heterostructures. Our results may be a new paradigm and reference for phosphorene-based heterostructures used as electrode materials of metal-ion batteries.