Atomic modeling for the initial stage of chromium passivation

The well-known anti-corrosive property of stainless steels is largely attributed to the addition of Cr,which can assist in forming an inert film on the corroding surface.To maximize the corrosion-resistant ability of Cr,a thorough study dealing with the passivation behaviors of this metal,including the structure and composition of the passive film as well as related reaction mechanisms,is required.Here,continuous electrochemical adsorptions of OH-groups of water molecules onto Cr terraces in acid solutions are investigated using DFT methods.Different models with various surface conditions are applied.Passivation is found to begin in the active region,and a fully coated surface mainly with oxide is likely to be the starting point of the passive region.The calculated limiting potentials are in reasonable agreement with passivation potentials observed via experiment.

High-performance oxygen reduction and evolution carbon catalysis： From mechanistic studies to device integration

能容易集成于存在的高效、便宜的氧减小和进化催化剂的发展设备为利用 O 2-H2 O 化学，例如再生燃料房间和金属空气电池。此处，我们报导 NH 3-activated 做 N 的层次碳(NHC ) 催化剂经由一条可伸缩的线路综合了，并且表明它的设备集成。NHC 催化剂为氧减小反应(ORR ) 和氧进化反应(OER ) 展出了好性能，当综合时，借助于电气化学的研究和评估示威了进一个再生燃料房间的氧电极。为 ORR 和 OER 观察的活动比得上最先进的磅和红外催化剂在碱的环境完成的那些。我们进一步通过密度为电气化学的活动作为活跃地点识别了碳缺点的关键角色功能的理论计算和高分辨率的 TEM 可视化。这个工作加亮 NHC 的潜力在再生燃料房间并且可能代替商业宝贵金属为断断续续的可更新的精力的划算的存储的金属空气电池。

Identifying factors controlling the selective ethane dehydrogenation on Pt-based catalysts from DFT based micro-kinetic modeling

Light olefins such as ethylene and propylene are important industrial feedstocks, having essential applications in the production of plastics, ethylbenzene, and ethylene dichloride [1]. Compared with the conventional route, in which alkane steam cracking (SC) at high temperature is applied to produce ethylene and propylene, the catalytic ethane/propane non-oxidative dehydrogenation (EDH/PDH) possess the advantages of high selectivity and low energy consumption. Industrially, Pt is the major component to catalyze this reaction, but it suffers from low selectivity and fast deactivation because of favorable coke formation [2].

Carbon flowers as electrocatalysts for the reduction of oxygen to hydrogen peroxide

Small-scale and decentralized production of H_(2)O_(2)via electrochemical reduction of oxygen is of great benefit,especially for sanitization,air and water purification,as well as for a variety of chemical processes.The development of low-cost and highperformance catalysts for this reaction remains a key challenge.Carbon-based materials have drawn substantial research efforts in recent years due to their advantageous properties,such as high chemical stability and high tunability in active sites and morphology.Deeper understanding of structure–activity relationships can guide the design of improved catalysts.We hypothesize that mass transport to active sites is of great importance,and herein we use carbon materials with unique flower-like superstructures to achieve high activity and selectivity for O2 reduction to H_(2)O_(2).The abundance of nitrogen active sites controlled by pyrolysis temperature resulted in high catalytic activity and selectivity for oxygen reduction reaction(ORR).The flower superstructure showed higher performance than the spherical nanoparticles due to greater accessibility to the active sites.Chemical activation improves the catalysts’performances further,driving the production of H_(2)O_(2)to a record-setting rate of 816 mmol·gcat^(−1)·h^(−1)using a bulk electrolysis setup.This work demonstrates the development of a highly active catalyst for the sustainable production of H_(2)O_(2)through rational design and synthetic control.The understanding from this work provides further insight into the design of future carbon-based electrocatalysts.

Transition-metal doped edge sites in vertically aligned MoS2 catalysts for enhanced hydrogen evolution

为象氢进化反应那样的电气化学的反应的高度活跃、便宜的催化剂(她的) 为有效精力的发展是关键的变换和存储技术。理论模拟在揭示在材料和他们的催化活动的电子结构之间的关联是有帮助的，并且指导改进催化剂的预言和发展。然而，在精确地设计需要的原子地点的困难在做在试验性、理论的结果之间的直接比较导致挑战。在瞬间 < 潜水艇 class= “ a-plus-plus ” > 2 , 而薹是惰性的，瞬间边被表明了为她活跃。用一条计算基于描述符的途径，我们预言由合并转变金属原子(Fe，公司， Ni，或 Cu ) ，薹地点应该也成为她活跃。垂直地站的、终止边的瞬间 < 潜水艇 class= “ a-plus-plus ” > 2 nanofilms 为验证这些预言提供一个明确的模型系统。转变金属做了瞬间 < 潜水艇 class= “ a-plus-plus ” > 2 nanofilms 表演交换水流密度由的增加至少双重，与理论计算一致。这个工作为由把倡导者合并到特别原子地点改进电气化学的催化剂，并且为使用明确的系统以便理解提升效果的起源开创进一步的机会。

Genetic algorithms for computational materials discovery accelerated by machine learning

Materials discovery is increasingly being impelled by machine learning methods that rely on pre-existing datasets.Where datasets are lacking,unbiased data generation can be achieved with genetic algorithms.Here a machine learning model is trained on-the-fly as a computationally inexpensive energy predictor before analyzing how to augment convergence in genetic algorithm-based approaches by using the model as a surrogate.This leads to a machine learning accelerated genetic algorithm combining robust qualities of the genetic algorithm with rapid machine learning.The approach is used to search for stable,compositionally variant,geometrically similar nanoparticle alloys to illustrate its capability for accelerated materials discovery,e.g.,nanoalloy catalysts.The machine learning accelerated approach,in this case,yields a 50-fold reduction in the number of required energy calculations compared to a traditional“brute force”genetic algorithm.This makes searching through the space of all homotops and compositions of a binary alloy particle in a given structure feasible,using density functional theory calculations.

Diphosphine-induced chiral propeller arrangement ofgold nanoclusters for singlet oxygen photogeneration

In this study, 1,2-bis（diphenylphosphino）ethane （dppe） ligands are used tosynthesize gold nanoclusters with an icosahedral Au13 core. The nanoclustersare characterized and formulated as [Au13（dppe）sCl2]C13 using synchrotronradiation X-ray diffraction, UV/Vis absorption spectroscopy, electrosprayionization mass spectrometry, and density functional theory （DFT） calculations.The bidentate feature of dppe ligands and the positions of coordinating surfacegold atoms induce a helical arrangement that forms a propeller-like structure,which reduces the symmetry of the gold nanocluster to C1. Therefore, dppeligands perform as a directing agent to create chiral an ansa metaUamacrocycle[Au13（dppe）sC12]3. nanocluster, as confirmed by simulated electronic circulardichroism spectrum. The highest occupied molecular orbital （HOMO）-lowestunoccupied molecular orbital （LUMO） gap of the [Au13（dppe）sC12]3. duster isdetermined as approx. 1.9 eV, and further confirmed by ultraviolet photoemissionspectroscopy analysis and DFT simulation. Furthermore, the photoactivityof [Au13（dppe）sC12]3＋ is investigated, with the nanocluster shown to possessnear-infrared photoluminescence properties, which can be employed for102 photogeneration. The quantum yield of 102 photogeneration using the[Au13（dppe）5C12]3. nanocluster is up to 0.71, which is considerably higher thanthose of anthracene （an organic dye）, and Au25 and Au38 nanoclusters.

Electronic structure factors and the importance of adsorbate effects in chemisorption on surface alloys

The chemisorption energy is an integral aspect of surface chemistry,central to numerous fields such as catalysis,corrosion,and nanotechnology.Electronic-structure-based methods such as the Newns-Anderson model are therefore of great importance in guiding the engineering of material surfaces with optimal properties.However,existing methods are inadequate for interpreting complex,multi-metallic systems.Herein,we introduce a physics-based chemisorption model for alloyed transition metal surfaces employing primarily metal d-band properties that accounts for perturbations in both the substrate and adsorbate electronic states upon interaction.Importantly,we show that adsorbate-induced changes in the adsorption site interact with its chemical environment leading to a second-order response in chemisorption energy with the d-filling of the neighboring atoms.We demonstrate the robustness of the model on a wide range of transition metal alloys with O,N,CH,and Li adsorbates yielding a mean absolute error of 0.13 eV versus density functional theory reference chemisorption energies.

A Bayesian framework for adsorption energy prediction on bimetallic alloy catalysts

For high-throughput screening of materials for heterogeneous catalysis,scaling relations provides an efficient scheme to estimate the chemisorption energies of hydrogenated species.However,conditioning on a single descriptor ignores the model uncertainty and leads to suboptimal prediction of the chemisorption energy.In this article,we extend the single descriptor linear scaling relation to a multi-descriptor linear regression models to leverage the correlation between adsorption energy of any two pair of adsorbates.With a large dataset,we use Bayesian Information Criteria(BIC)as the model evidence to select the best linear regression model.Furthermore,Gaussian Process Regression(GPR)based on the meaningful convolution of physical properties of the metal-adsorbate complex can be used to predict the baseline residual of the selected model.This integrated Bayesian model selection and Gaussian process regression,dubbed as residual learning,can achieve performance comparable to standard DFT error(0.1 eV)for most adsorbate system.For sparse and small datasets,we propose an ad hoc Bayesian Model Averaging(BMA)approach to make a robust prediction.With this Bayesian framework,we significantly reduce the model uncertainty and improve the prediction accuracy.The possibilities of the framework for high-throughput catalytic materials exploration in a realistic setting is illustrated using large and small sets of both dense and sparse simulated dataset generated from a public database of bimetallic alloys available in Catalysis-Hub.org.

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

镍铁分层的双氢氧化物(NiFe-LDH ) nanosheets 显示出最佳的氧进化反应(OER ) 性能；然而，在 OER 活动的设置的离子的角色仍然保持不清楚。在这个工作，我们证明 NiFe-LDHs 的活动能被设置的阴离子与不同氧化还原作用潜力定制。而 NiFe-LDHs 与高氧化还原作用潜力(低减少能力)的阴离子设置了，有低氧化还原作用潜力(高减少能力)的阴离子的置闰例如次磷酸盐，与 240 mV 的低 OER 过电位和 36.9 mV/dec 的一个小 Tafel 斜坡导致 NiFe-LDHs ，例如 fluorion ，显示出 370 mV 的高过电位和 80.8 mV/dec 的一个 Tafel 斜坡。OER 活动与标准氧化还原作用潜力显示出令人吃惊的线性关联。密度功能的理论计算和 X 光检查光电子光谱学分析显示设置的阴离子改变在表面暴露了的金属原子的电子结构。有低标准氧化还原作用潜力和强壮的减少能力的阴离子把更多的电子转移到氢氧化物层。这增加表面金属地点的电子密度并且稳定他们的高原子价的状态，其形成在 OER 过程以前作为关键步被知道。