Spontaneous decoration of ionic compounds at perovskite interfaces to achieve 23.38% efficiency with 85% fill factor in NiO_X-based perovskite solar cells

Inorganic hole transport materials, particularly NiO_X, have shown considerable promise in boosting the efficiency and stability of perovskite solar cells. However, a major barrier to commercialization of NiO_X-based perovskite solar cells with positive-intrinsic-negative architectures is their direct contact with the absorbing layer, which can lead to losses of photovoltage and fill factor. Furthermore, highly positive under-coordinated Ni cations degrade the perovskite at the interface. Here, we address these issues with the use of an ionic compound(QAPyBF_(4)) as an additive to passivate defects throughout the perovskite layer and improve carrier conduction and interactions with under-coordinated Ni cations. Specifically,the highly electronegative inorganic anion [BF_(4)]~- interacts with the NiO_x/perovskite interface to passivate under-coordinated cations(Ni^(≥3+)). Accordingly, the decorated cells achieved a power conversion efficiency of 23.38% and a fill factor of 85.5% without a complex surface treatment or NiO_X doping.

铜及铜合金作为免疫和抗菌元素的综述

讨论铜与人、细菌之间的关系。铜在人体免疫中发挥重要作用。在推荐摄入量下,铜可以增强人体的免疫防御反应。本文主要讨论铜的抗菌活性和抗菌机制。结论表明,铜的抗菌活性受细菌中铜稳态机制、粘附、湿度、菌株特异性以及抗菌剂制备方法的影响。对于颗粒抗菌和表面抗菌材料,讨论几种制备方法,如溶胶−凝胶法、冷喷涂法和生物合成法,分别属于化学合成、物理合成和生物合成法。溶胶−凝胶法有助于颗粒抗菌和表面抗菌材料的制备;冷喷涂技术可以应用于表面抗菌铜的合成;生物合成是一种可应用于纳米颗粒抗菌剂制备的新技术。

The geothermal formation mechanism in the Gonghe Basin: Discussion and analysis from the geological background

The Gonghe Basin,a Cenozoic down-warped basin,is located in the northeastern part of the Qinghai-Xizang (Tibetan) Plateau,and spread over important nodes of the transfer of multiple blocks in the central orogenic belt in the NWW direction.It is also called “Qin Kun Fork” and “Gonghe Gap”.The basin has a high heat flow value and obvious thermal anomaly.The geothermal resources are mainly hot dry rock and underground hot water.In recent years,the mechanism of geothermal formation within the basin has been controversial.On the basis of understanding the knowledge of predecessors,this paper proposes the geothermal formation mechanism of the “heat source–heat transfer–heat reservoir and caprock–thermal system”of the Gonghe Basin from the perspective of a geological background through data integrationintegrated research-expert,discussion-graph,compilation-field verification and other processes: (1) Heat source: geophysical exploration and radioisotope calculations show that the heat source of heat in the basin has both the contribution of mantle and the participation of the earth's crust,but mainly the contribution of the deep mantle.(2) Heat transfer: The petrological properties of the basin and the exposed structure position of the surface hot springs show that one transfer mode is the material of the mantle source upwells and invades from the bottom,directly injecting heat;the other is that the deep fault conducts the deep heat of the basin to the middle and lower parts of the earth's crust,then the secondary fracture transfers the heat to the shallow part.(3) Heat reservoir and caprock: First,the convective strip-shaped heat reservoir exposed by the hot springs on the peripheral fault zone of the basin;second,the underlying hot dry rock layered heat reservoir and the upper new generation heat reservoir and caprock in the basin revealed by drilling data.(4) Thermal system: Based on the characteristics of the “heat source-heat transfer-heat reservoir and caprock”,it is preliminarily believed that the Gonghe Basin belongs to the non-magmatic heat source hydrothermal geothermal system (type II21) and the dry heat geothermal system (type II22).Its favorable structural position and special geological evolutionary history have given birth to a unique environment for the formation of the geothermal system.There may be a cumulative effect of heat accumulation in the eastern part of the basin,which is expected to become a favorable exploration area for hot dry rocks.

Unraveling the catalytically active phase of carbon dioxide hydrogenation to methanol on Zn/Cu alloy: Single atom versus small cluster

Methanol synthesis from CO_(2)hydrogenation catalyzed by Zn/Cu alloy has been widely studied,but there is still debate on its catalytic active phase and whether the Zn can be oxidized during the reaction process.What is more,as Zn atoms could locate on Zn/Cu alloy surface in forms of both single atom and cluster,how Zn surface distribution affects catalytic activity is still not clear.In this work,we performed a systematic theoretical study to compare the mechanistic natures and catalytic pathways between Zn single atom and small cluster on catalyst surface,where the surface oxidation was shown to play the critical role.Before surface oxidation,the Zn single atom/Cu is more active than the Zn small cluster/Cu,but its surface oxidation is difficult to take place.Instead,after the easy surface oxidation by CO_(2)decomposition,the oxidized Zn small cluster/Cu becomes much more active,which even exceeds the hardlyoxidized Zn single atom/Cu to become the active phase.Further analyses show this dramatic promotion of surface oxidation can be ascribed to the following factors:i)The O from surface oxidation could preferably occupy the strongest binding sites on the center of Zn cluster.That makes the O intermediates bind at the Zn/Cu interface,preventing their too tight binding for further hydrogenation;ii)The higher positive charge and work function on the oxidized surface could also promote the hydrogenation of O intermediates.This work provided one more example that under certain condition,the metal cluster can be more active than the single atom in heterogeneous catalysis.

Exposing Cu-rich {110} active facets in PtCu nanostars for boosting electrochemical performance toward multiple liquid fuels electrooxidation

In catalysis,tuning the structural composition of the metal alloy is known as an efficient way to optimize the catalytic activity.This work presents the synthesis of compositional segregated six-armed PtCu nanostars via a facile solvothermal method and their distinct composition-structure-dependent performances in electrooxidation processes.The alloy is shown to have a unique six arms with a Cu-rich dodecahedral core,mainly composed of {110} facets and exhibit superior catalytic activity toward alcohols electrooxidation compared to the hollow counterpart where Cu was selectively etched.Density functional theory (DFT) calculations suggest that the formation of hydroxyl intermediate (OH^*) is crucial to detoxify CO poisoning during the electrooxidation processes.The addition of Cu is found to effectively adjust the d band location of the alloy catalyst and thus enhance the formation of ^*OH intermediate from water splitting,which decreases the coverage of ^*CO intermediate.Our work demonstrates that the unique compositional anisotropy in alloy catalyst may boost their applications in electrocatalysis and provides a methodology for the design of this type catalyst.

Rational design of copper-based single-atom alloy catalysts for electrochemical CO_(2)reduction

Electrochemical CO_(2)-reduction reaction(CO_(2)RR)is a promising way to alleviate energy crisis and excessive carbon emission.The Cu-based electrocatalysts have been considered for CO_(2)RR to generate hydrocarbons and alcohols.However,the application of Cu electrocatalysts has been restricted by a high onset potential for CO_(2)RR and low selectivity.In this study,we have designed a series of Cu-based single-atom alloy catalysts(SAAs),denoted as TM1/Cu(111),by doping isolated 3dtransition metal(TM)atom onto the Cu(111)surface.We theoretically evaluated their stability and investigated the activity and selectivity toward CO_(2)RR.Compared to the pure Cu catalyst,the majority TM1/Cu(111)catalysts are more favorable for hydrogenating CO_(2)and can efficiently avoid the hydrogen-evolution reaction due to the strong binding of carbonaceous intermediates.Based on the density functional theory calculations,instead of the HCOOH or CO products,the initial hydrogenation of CO_(2)on SAAs would form the*CO intermediate,which could be further hydrogenated to produce methane.In addition,we have identified the bond angle of adsorbed*CO_(2)can describe the CO_(2)activation ability of TM1/Cu(111)and the binding energy of*OH can describe the CO_(2)RR activity of TM1/Cu(111).We speculated that the V/Cu(111)can show the best activity and selectivity for CO_(2)RR among all the 3d-TM-doped TM1/Cu(111).This work could provide a rational guide to the design of new type of single-atom catalysts for efficient CO_(2)RR.

Au–Pd单原子合金(SAA)催化剂的催化机理和成键分析:CO氧化反应

单原子催化剂(SACs)在催化科学领域引起了人们的广泛关注,包括被称为单原子合金(SAAs)的包含金属-金属键合的双金属催化剂.本文通过量子化学计算方法研究了Au–Pd单原子合金模型Au37Pd1上CO氧化反应的催化机理和成键分析,确定了CO@Au–Pd,O2@Au–Pd和CO/O2@Au–Pd等吸附构型的几何结构以及吸附物与底物间的结合能.Pd原子位于核芯位置的核-壳结构被证实为Au–Pd单原子合金的最稳定构型,该结构的稳定性来源于Pd原子向Au原子的电荷转移.根据结合能和化学成键分析,CO和O2分子均优先吸附在配位数低且位于顶点位置的Pd原子上.本文报道了一种新的CO和O2共吸附结构,其中CO和O2分别在两个相邻Au–Pd键上以垂直和平行桥联方式吸附,该Au–Pd单原子合金的CO氧化反应具有低能垒且遵循Langmuir-Hinshewood(L-H)机理.本文探讨了单原子合金催化剂中单原子在催化反应中的重要作用,可以为设计具有优异催化活性的新型单原子合金催化剂提供依据.

超细PtCu纳米线的表面结构调控及其增强的醇类电催化氧化作用

铂基纳米催化剂的表面结构调控是提升其电催化性能和实现多功能性的有效途径.本工作报道了两种超细PtCu纳米线(光滑型和粗糙型)的湿化学合成方法及其电催化醇氧化的性能.研究结果表明,粗糙型PtCu合金表面具有丰富的原子台阶,对多种电化学反应具有较好的催化活性.密度泛函理论模拟表明,粗糙型PtCu纳米线具有较好的反应活性,这是由于Pt-Cu位点之间的协同作用促进了反应过程中水的解离和羧基中间体的脱氢.本工作为能源相关电催化体系中合金纳米催化剂的合理设计提供了思路.

Single-element amorphous palladium nanoparticles formed via phase separation

Physically vitrifying amorphous single-element metal requires ultrahigh cooling rates,which are still unachievable for most of the closest-packed metals.Here,we report a facile chemical synthetic strategy for single-element amorphous palladium nanoparticles with a purity of 99.35 at.%±0.23 at.%from palladium–silicon liquid droplets.In-situ transmission electron microscopy directly detected the solidification of palladium and the separation of silicon.Further hydrogen absorption experiment showed that the amorphous palladium expanded little upon hydrogen uptake,exhibiting a great potential application for hydrogen separation.Our results provide insight into the formation of amorphous metal at nanoscale.

Exploring electronic-level principles how size reduction enhances nanomaterial surface reactivity through experimental probing and mathematical modeling

Size reduction can generally enhance the surface reactivity of inorganic nanomaterials.The origin of this nano-effect has been ascribed to ultrasmall size,large specific surface area,or abundant defects,but the most intrinsic electronic-level principles are still not fully understood yet.By combining experimental explorations and mathematical modeling,herein we propose an electronic-level model to reveal the physicochemical nature of size-dependent nanomaterial surface reactivity.Experimentally,we reveal that competitive redistribution of surface atomic orbitals from extended energy band states into localized surface chemical bonds is the critical electronic process of surface chemical interactions,using H_(2)O_(2)-TiO_(2)chemisorption as a model reaction.Theoretically,we define a concept,orbital potential(G),to describe the electronic feature determining the tendency of orbital redistribution,and deduce a mathematical model to reveal how size modulates surface reactivity.We expose the dual roles of size reduction in enhancing nanomaterial surface reactivity-inversely correlating to orbital potential and amplifying the effects of other structural factors on surface reactivity.

Theory-Driven Design of Electrocatalysts for the Two-Electron Oxygen Reduction Reaction Based on Dispersed Metal Phthalocyanines

The two-electron electrochemical reduction of oxygen is an appealing approach to produce hydrogen peroxide.Metal and heteroatom-doped carbon(M–X/C)materials have recently been recognized as compelling catalysts for this process,but their performance improvement is generally hindered by the ill-defined structures of active sites.Herein,we demonstrate a theory-driven design of catalysts for oxygen reduction reactions based on molecularly dispersed electrocatalysts(MDEs)with metal phthalocyanines on carbon nanotubes.Density functional theory calculations suggest that nickel phthalocyanine(NiPc)favors the formation of*H_(2)O_(2) over*O,thus acting as a selective catalyst for peroxide production.NiPc MDE shows high peroxide yields of∼83%,superior to the aggregated NiPc and pyrolyzed Ni–N/C catalysts.The performance is further enhanced by the introduction of the cyano group(CN).NiPc–CN MDE exhibits∼92%peroxide yields and good stability.Our studies provide a new perspective for the development of heterogeneous electrocatalysts for hydrogen peroxide production from metal macrocyclic complexes.