The Activity Improvement of the TM3(hexaiminotriphenylene)2 Monolayer for Oxygen Reduction Electrocatalysis: A Density Functional Theory Study

Synergistic Niobium Doped Two-Dimensional Zirconium Diselenide: An Efficient Electrocatalyst for O2 Reduction Reaction

The development of high-activity and low-price cathodic catalysts to facilitate the electrochemically sluggish O2 reduction reaction (ORR) is very important to achieve the commercial application of fuel cells. Here, we have investigated the electrocatalytic activity of the two-dimensional single-layer Nb-doped zirconium diselenide (2D Nb-ZrSe2) toward ORR by employing the dispersion corrected density functional theory (DFT-D) method. Through our study, we computed structural properties, electronic properties, and energetics of the 2D Nb-ZrSe2 and ORR intermediates to analyze the electrocatalytic performance of 2D Nb-ZrSe2. The electronic property calculations depict that the 2D monolayer ZrSe2 has a large band gap of 1.48 eV, which is not favorable for the ORR mechanism. After the doping of Nb, the electronic band gap vanishes, and 2D Nb-ZrSe2 acts as a conductor. We studied both the dissociative and the associative pathways through which the ORR can proceed to reduce the oxygen molecule (O2). Our results show that the more favorable path for O2 reduction on the surface of the 2D Nb-ZrSe2 is the 4e- associative path. The detailed ORR mechanisms (both associated and dissociative) have been explored by computing the changes in Gibbs free energy (ΔG). All of the ORR reaction intermediate steps are thermodynamically stable and energetically favorable. The free energy profile for the associative path shows the downhill behavior of the free energy vs the reaction steps, suggesting that all ORR intermediate structures are catalytically active for the 4e- associative path and a high 4e- reduction pathway selectivity. Therefore, 2D Nb-ZrSe2 is a promising catalyst for the ORR, which can be used as an alternative ORR catalyst compared to expensive platinum (Pt).

Facile fabrication of hierarchical Rh2Ir alloy nanodendrites with excellent HER performance in a broad pH range

Hierarchical Rh₂Ir alloy nanodendrites were prepared via a facile oil-bath method, which exhibits excellent HER performance in a broad pH range.

Isolated Au Atom Anchored on Porous Boron Nitride as a Promising Electrocatalyst for Oxygen Reduction Reaction (ORR): A DFT Study

The development of efficient, stable, and low-cost catalytic material for the oxygen reduction reaction (ORR) is currently highly desirable but challenging. In this work, based on first-principles calculation, the stabilities, catalytic activities and catalytic mechanisms of isolated Au atom supported on defective porous BN (p-BN) have been studied in detail. The results reveal that the defective p-BN anchor Au atom strongly to ensure the stability of Au/p-BN. Based on frontier molecular orbital and charge-density analysis, isolated Au atom supported on porous BN with V_N defect (Au/p-BN-V_N) is an effective ORR catalyst. Especially, the low barriers of the formation (0.38 eV) and dissociation (0.31 eV) of ^*OOH and the instability of H₂O₂ on Au/p-BN-V_N catalyst suggest that ORR proceeds via 4-electron pathway. Along the favorable pathway, the reduction of O₂ to ^*OOH is the rate-limiting step with the largest activation barrier of 0.38 eV and the maximum free energy change is 1.88 eV. Our results provide a useful guidance for the design and fabrication of new Au-base catalyst with high-efficiency and are beneficial for the developing of novel isolated metal atom catalysts for ORR.

How to Boost the Activity of the Monolayer Pt Supported on TiC Catalysts for Oxygen Reduction Reaction: A Density Functional Theory Study

Developing the optimized electrocatalysts with high Pt utilization as well as the outstanding performance for the oxygen reduction reaction (ORR) has raised great attention. Herein, the effects of the interlayer ZrC, HfC, or TiN and the multilayer Pt shell on the adsorption ability and the catalytic activity of the TiC@Pt core-shell structures are systemically investigated by density functional theory (DFT) calculations. For the sandwich structures, the presence of TiN significantly enhances the adsorption ability of the Pt shell, leading to the deterioration of the activity whilst the negligible influence of the ZrC and HfC insertion results the comparable performance with respect to TiC@Pt_1ML. In addition, increasing the thickness of the Pt shell reduces the oxyphilic capacity and then mitigates the OH poisoning. From the free energy plots, the superior activity of TiC@Pt_2ML is identified in comparison with 1ML and 3ML Pt shell. Herein, the improved activity with its high Pt atomic utilization makes the potential TiC@Pt_2ML electrocatalyst for the future fuel cells.

Understanding electro-catalysis by using density functional theory

DFT calculations are indispensable for understanding the electro-catalysis through explanation of the experimental phenomena, prediction of experimental results, and guiding of the experimental investigation.