Oxygen reduction reaction on Pt(1 1 1), Pt(2 2 1), and Ni/Au1Pt3(2 2 1) surfaces: Probing scaling relationships of reaction energetics and interfacial composition

Structure evolution and durability of Metal-Nitrogen-Carbon (M = Co, Ru, Rh, Pd, Ir) based oxygen evolution reaction electrocatalyst: A theoretical study

Developing low-cost, high activity and stability oxygen evolution reaction (OER) catalysts is significantly important but still challenging for water electrolyzers. In this work, we calculated the OER activity and stability of Metal-Nitrogen-Carbon (MNC, M = Co, Ru, Rh, Pd, Ir) based electrocatalyst with different structures (MN₄C₈, MN₄C₁₀, MN₄C₁₂) using density functional theory (DFT) method. These electrocatalysts were divided into three groups based on the value of ΔG_*OH, that is ΔG_*OH > 1.53 eV (PdN₄C₈, PdN₄C₁₀, PdN₄C₁₂), ΔG_*OH < 1.23 eV (RuN₄C₈, RuN₄C₁₀, RuN₄C₁₂, CoN₄C₈, CoN₄C₁₀) and 1.23 eV < ΔG_*OH < 1.53 eV (RhN₄C₈, RhN₄C₁₀, RhN₄C₁₂, IrN₄C₈, IrN₄C₁₀, IrN₄C₁₂, CoN₄C₁₂), and ΔG_*OH determine whether the structure evolution will appear. The results proved that MNC (M = Rh, Ir) with 1.23 eV < ΔG_*OH < 1.53 eV shows higher OER activity due to moderate binding energy between reaction intermediates and MNC. Furthermore, these catalysts could maintain MNC structure without further oxidation and structural evolution under working conditions (high temperature, dynamic condition, local electric field and strong specific adsorption), therefore show excellent stability. However, MNC electrocatalyst with ΔG_*OH > 1.53 eV or ΔG_*OH < 1.23 eV revealed less stability under working conditions, due to their low intrinsic stability or structural evolution under working conditions, respectively. In conclusion, we proposed a comprehensive evaluation method for MNC electrocatalysts by taking ΔG_*OH as the screening criterion for OER activity and stability, as well as ΔE_b under working condition as descriptor of stability. This is of great significance for the design and screening of ORR, OER and HER electrocatalysts under working conditions.

Kinetic Monte Carlo simulations for heterogeneous catalysis: Fundamentals, current status, and challenges

Kinetic Monte Carlo (KMC) simulations in combination with first-principles (1p)-based calculations are rapidly becoming the gold-standard computational framework for bridging the gap between the wide range of length scales and time scales over which heterogeneous catalysis unfolds. 1p-KMC simulations provide accurate insights into reactions over surfaces, a vital step toward the rational design of novel catalysts. In this Perspective, we briefly outline basic principles, computational challenges, successful applications, as well as future directions and opportunities of this promising and ever more popular kinetic modeling approach.

Stepped M@Pt(211) (M = Co, Fe, Mo) single-atom alloys promote the deoxygenation of lignin-derived phenolics: mechanism, kinetics, and descriptors

HDO of lignin-derived phenolics on stepped M@Pt(211) (M = Co, Fe, Mo) single-atom alloy was computationally explored. Either C–O bond length or *OH binding energy was confirmed as an effective catalytic descriptor for predicting HDO performance.

Synergy of tellurium and defects in control of activity of phosphorene for oxygen evolution and reduction reactions

Developing low-cost and metal-free electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is desirable for renewable energy technologies. Recent experiments show that tellurium (Te) atoms can be effectively doped into black phosphorus (BP) nanosheets, and they greatly improve its OER catalytic performance. However, the specific active sites and microscopic configurations in the atomic-scale are still ambiguous. Here, we show that the doped Te atoms prefer to bond with each other to form clusters in phosphorene and they can be further stabilized by various intrinsic defects (Stone-Wales, single vacancy defects and zigzag nanoribbon). Benefiting from the reduced binding strength of O*, Te dopants and intrinsic defects synergistically boost the catalytic activity of phosphorene. The best OER catalytic activity could be realized in the cluster SW2-Te1p (Stone-Wales defect decorated by one Te atom). For ORR, the cluster Pri-Te3p (pristine phosphorene decorated by three Te atoms) exhibits optimal catalytic activity. Calculated ORR/OER potential gaps indicate that the SW2-Te3p cluster most likely acts as the efficient bifunctional catalytic site for both ORR and OER.

The mechanism and activity of oxygen reduction reaction on single atom doped graphene: a DFT method

Heteroatom doped graphene as a single-atom catalyst for oxygen reduction reaction (ORR) has received extensive attention in recent years. In this paper, the ORR activity of defective graphene anchoring single heteroatom (IIIA, IVA, VA, VIA and VIIA) was systematically investigated using a dispersion-corrected density functional theory method. For all of the 34 catalysts, 14 of which were further analyzed, and the Gibbs free energy of each elementary reaction was calculated. According to the scaling relationship between ΔG_OOH* and ΔG_OH*, we further analyzed the rate-determining step of the remaining 20 catalysts. The results show that when the ORR reaction proceeds in the path O₂ → OOH → O → OH → H₂O, the reaction energy barriers are lower than 0.8 eV for Te-SV, Sb-DV, Pb-SV, Pb-DV, As-SV, As-DV, B-SV, Sn-SV and N-SV. Our result provides a theoretical basis for further exploration of carbon-based single-atom catalysts for ORR.

Heteroatom doped graphene as a single-atom catalyst for oxygen reduction reaction (ORR) has received extensive attention in recent years.

C2N-graphene supported single-atom catalysts for CO2 electrochemical reduction reaction: mechanistic insight and catalyst screening

Single-atom catalysts (SACs) have emerged as an excellent platform for enhancing catalytic performance. Inspired by the recent experimental synthesis of nitrogenated holey 2D graphene (C2N-h2D) (Mahmood et al., Nat. Commun., 2015, 6, 6486-6493), we report density functional theory calculations combined with computational hydrogen electrode model to show that C2N-h2D supported metal single atoms (M@C2N) are promising electrocatalysts for CO2 reduction reaction (CO2 RR). M confined at pyridinic N6 cavity promotes activation of inert O[double bond, length as m-dash]C[double bond, length as m-dash]O bonds and subsequent protonation steps, with *COOH → *CO → CHO predicted to be the primary pathway for producing methanol and methane. It is found that *CO + H+ + e- → *CHO is most likely to be the potential determining step; breaking the scaling relation of *CO and *CHO binding on M@C2N SACs may simply be a rare event that is sensitively controlled by the detailed geometry of the adsorbate. Among twelve metals screened, M@C2N SACs where M = Ti, Mn, Fe, Co, Ni, Ru were identified to be effective in catalyzing CO2 RR with lowered overpotentials (0.58 V-0.80 V).