Controllable and large-area growth of ZnO nanosheet arrays under ambient condition as superior anodes for scalable aqueous batteries

Two-dimensional(2D)oxides have been the focus of substantial research interest recently,owing to their fascinating physico-chemical properties.However,fabrication of large-area 2D oxide materials in a controlled manner under mild conditions still remains a formidable challenge.Herein,we develop a facile and universal strategy based on the sonochemistry approach for controllable and large-area growth of quasi-aligned single-crystalline ZnO nanosheets on a Zn substrate(Zn@SC-ZnO)under ambient conditions.The obtained ZnO nanosheets possess the desired exclusively exposed(001)facets,which have been confirmed to play a critical role in significantly reducing the activation energy and facilitating the stripping/plating processes of Zn.Accordingly,the constructed Zn@SC-ZnO||Zn@SC-ZnO symmetric cell has very low polarization overpotential down to~20 mV,with limited dendrite growth and side reactions for Zn anodes.The developed Zn@SC-ZnO//MnO_(2)aqueous Zn-ion batteries(ZIBs)show a voltage efficiency of 88.2%under 500 mA g^(-1)at the stage of 50%depth of discharge,which is state of the art for ZIBs reported to date.Furthermore,the as-assembled large-size cell(5 cm×5 cm)delivers an open circuit potential of 1.648 V,and can be robustly operated under a high current of 20 mA,showing excellent potential for future scalable applications.

Enhancing fly ash utilization in backfill materials treated with CO_(2)carbonation under ambient conditions

The environmental concerns resulting from coal-fired power generation that produces large amounts of CO_(2)and fly ash are of great interest.To mitigate,this study aims to develop a novel carbonated CO_(2)-fly ash-based backfill(CFBF)material under ambient conditions.The performance of CFBF was investigated for different fly ash-cement ratios and compared with non-CO_(2)reacted samples.The fresh CFBF slurry conformed to the Herschel-Bulkley model with shear thinning characteristics.After carbonation,the yield stress of the fresh slurry increased significantly by lowering fly ash ratio due to gel formation.The setting times were accelerated,resulting in approximately 40.6%of increased early strength.The final strength decreased when incorporating a lower fly ash ratio(50%and 60%),which was related to the existing heterogeneous pores caused by rapid fluid loss.The strength increased with fly ash content above 70%because additional C-S(A)-H and silica gels were characterized to precipitate on the grain surface,so the binding between particles increased.The C-S(A)-H gel was developed through the pozzolanic reaction,where CaCO_(3)was the prerequisite calcium source obtained in the CO_(2)-fly ash reaction.Furthermore,the maximum CO_(2)uptake efficiency was 1.39 mg-CO_(2)/g-CFBF.The CFBF material is feasible to co-dispose CO_(2)and fly ash in the mine goaf as negative carbon backfill materials,and simultaneously mitigates the strata movement and water lost in post-subsurface mining.

Porous LaFeO3 nanofiber with oxygen vacancies as an efficient electrocatalyst for N2 conversion to NH3 under ambient conditions

Electrocatalytic N2 reduction to NH3 under ambient conditions is an eco-friendly and sustainable alternative to the traditional Haber-Bosch process. However, inhibited by the high activation barrier of N2, this process needs efficient electrocatalysts to adsorb and activate the N2, enabling the N2 reduction reaction(NRR). Herein, we report that porous LaFeO3 nanofiber with oxygen vacancies acts as an efficient NRR electrocatalyst with abundant active sites to enhance the adsorption and activation of N2. When tested in 0.1 M HCl, such electrocatalyst achieves a high Faradaic efficiency of 8.77% and a large NH3 yield rate of 18.59 μg h–1 mgcat–1.at-0.55 V versus reversible hydrogen electrode. This catalyst also shows high long-term electrochemical stability and excellent selectivity for NH3 formation. Density functional theory calculations reveal that, by introducing oxygen vacancy on LaFeO3, the subsurface metallic ions are exposed with newly localized electronic states near the Fermi level, which facilitates the adsorption and activation of N2 molecules as well as the subsequent hydrogenation reactions.

Defect and interface engineering for electrochemical nitrogen reduction reaction under ambient conditions

Electrochemical nitrogen reduction reaction(e-NRR)under ambient conditions is an emerging strategy to tackle the hydrogen-and energy-intensive operations for traditional Haber-Bosch process in industrial ammonia(NH_(3))synthesis.However,the e-NRR performance is currently impeded by the inherent inertness of N_(2) molecules,the extremely slow kinetics and the overwhelming competition from the hydrogen evolution reaction(HER),all of which cause unsatisfied yield and ammonia selectivity(Faradaic efficiency,FE).Defect and interface engineering are capable of achieving novel physical and chemical properties as well as superior synergistic effects for various electrocatalysts.In this review,we first provide a general introduction to the NRR mechanism.We then focus on the recent progress in defect and interface engineering and summarize how defect and interface can be rationally designed and functioned in NRR catalysts.Particularly,the origin of superior NRR catalytic activity by applying these approaches was discussed from both theoretical and experimental perspectives.Finally,the remaining challenges and future perspectives in this emerging area are highlighted.It is expected that this review will shed some light on designing NRR electrocatalysts with excellent activity,selectivity and stability.

Theoretical analysis of the surface temperature regulation of an infrared false target subjected to periodical ambient conditions

Infrared false target is an important mean to induce the infrared-guided weapons,and the key issue is how to keep the surface temperature of the infrared false target to be the same as that of the object to be protected.One-dimensional heat transfer models of a metal plate and imitative material were established to explore the influences of the thermophysical properties of imitative material on the surface temperature difference（STD） between the metal plate and imitative material which were subjected to periodical ambient conditions.It is elucidated that the STD is determined by the imitative material’s dimensionless thickness（dim*,） and the thermal inertia(Pim).When dim* is above 1.0,the STD is invariable as long as Pim is a constant.And if the dimensionless thickness of metal plate（d,m*） is also larger than 1.0,the STD approaches to zero as long as Pimis the same as the thermal inertia of metal plate（Pm）.When dim* is between 0.08 and 1,the STD varies irregularly with Pim and dim*.However,if dm* is also in the range of 0.08-1,the STD approaches to zero on condition that Pim=Pm and dim*= dm*.If dim*,is below 0.08,the STD is unchanged when Pimdim* is a constant.And if dm* is also less than 0.08,the STD approaches to zero as long as Pimdim* = Pmdm*.Furthermore,an applicationoriented discussion indicates that the imitative material can be both light and thin via the application of the phase change material with a preset STD because of its high specific heat capacity during the phase transition process.

Ultrafast metal oxide reduction at Pd/PdO_(2) interface enables onesecond hydrogen gas detection under ambient conditions

Here,we report a Pd/PdO_(x) sensing material that achieves 1-s detection of 4% H_(2) gas(i.e.,the lower explosive limit concentration for H_(2))at room temperature in air.The Pd/PdO_(x) material is a network of interconnected nanoscopic domains of Pd,PdO,and PdO_(2).Upon exposure to 4% H_(2),PdO and PdO_(2) in the Pd/PdO_(x) are immediately reduced to metallic Pd,generating over a>90% drop in electrical resistance.The mechanistic study reveals that the Pd/PdO_(2) interface in Pd/PdOx is responsible for the ultrafast PdO_(x) reduction.Metallic Pd at the Pd/PdO_(2) interface enables fast H_(2) dissociation to adsorbed H atoms,significantly lowering the PdO2 reduction barrier.In addition,control experiments suggest that the interconnectivity of Pd,PdO,and PdO2 in our Pd/PdO_(x) sensing material further facilitates the reduction of PdO,which would otherwise not occur.The 1-s response time of Pd/PdO_(x) under ambient conditions makes it an excellent alarm for the timely detection of hydrogen gas leaks.

Controllable growth of single-crystalline zinc oxide nanosheets under ambient condition toward ammonia sensing with ultrahigh selectivity and sensitivity

To date,the synthesis of crystalline ZnO nanostructures was often performed under high temperatures and/or high pressures with tiny output,which limits their commercial applications.Herein,we report the progress on synthesizing single-crystalline ZnO nanosheets under ambient conditions(i.e.,room temperature(RT)and atmospheric pressure)based on a sonochemistry strategy.Furthermore,their controllable growth is accomplished by adjusting the pH values of solutions,enabling the tailored crystal growth habits on the polar-charged faces of ZnO along c-axis.As a proof of concept for their potential applications,the ZnO nanosheets exhibit highly efficient performance for sensing ammonia at RT,with ultrahigh sensitivity(S=610 at 100 ppm),excellent selectivity,rapid detection(response time/recover time=70 s/4 s),and outstanding detection limit down to 0.5 ppm,superior to those of all pure ZnO nanostructures and most ZnO-based composite counterparts ever reported.The present work might open a door for controllable production of ZnO nanostructures under mild conditions,and facilitate the exploration of modern gas sensors for detecting gaseous molecules at RT,which underscores their potential toward practical applications in opto-electronic nanodevices.

Near ambient condition hydrogen storage in a synergized tri-component hydride system

Subject Code:H07 With the support from the National Natural Science Foundation of China and HGZ-CAS,a collaborative study by the research groups led by Prof.Chen Ping(陈萍)from Dalian Institute of Chemical Physics,Chinese Academy of Sciences and Prof.M.Dornheim,Helmholtz-Zentrum Geesthacht,Germany

Crystallization and Orientation Modulation Enable Highly Efficient Doctor-Bladed Perovskite Solar Cells

With the rapid rise in perovskite solar cells(PSCs)performance,it is imperative to develop scalable fabrication techniques to accelerate potential commercialization.However,the power conversion efficiencies(PCEs)of PSCs fabricated via scalable two-step sequential deposition lag far behind the state-of-the-art spin-coated ones.Herein,the additive methylammonium chloride(MACl)is introduced to modulate the crystallization and orientation of a two-step sequential doctorbladed perovskite film in ambient conditions.MACl can significantly improve perovskite film quality and increase grain size and crystallinity,thus decreasing trap density and suppressing nonradiative recombination.Meanwhile,MACl also promotes the preferred face-up orientation of the(100)plane of perovskite film,which is more conducive to the transport and collection of carriers,thereby significantly improving the fill factor.As a result,a champion PCE of 23.14%and excellent longterm stability are achieved for PSCs based on the structure of ITO/SnO_(2)/FA_(1-x)MA_xPb(I_(1-y)Br_y)_3/Spiro-OMeTAD/Ag.The superior PCEs of 21.20%and 17.54%are achieved for 1.03 cm~2 PSC and 10.93 cm~2 mini-module,respectively.These results represent substantial progress in large-scale two-step sequential deposition of high-performance PSCs for practical applications.

房间空调器低环境温度制冷控制策略分析及试验验证

通过对房间空调器室外机风机控制策略、蒸发器冻结保护策略、电子膨胀阀制冷剂流量调节策略、压缩机运行频率控制策略等进行优化,提升低环境温度下冷凝压力和蒸发压力,从而提升低环境温度下的制冷量。研究结果表明,通过控制策略的调整及应用,环境温度为-15℃时空调器制冷量为环境温度为35℃时制冷量的69.8%,较改进前机型提升13.2%;环境温度在-6℃以下时,室外机风机会进入启停控制,室外机风机启停最小时间间隔80s,室外机风机停止期间系统最高压力为3.88MPa,在安全可靠的时间与压力范围内。

关于一拖多空调环境温度检测准确性优化的研究

空调器的作用是通过调节室内温湿度达到设定标准,满足用户对室内环境的舒适要求。目前市场上的一拖多空调器因温度传感器检测值存在较大偏差,导致部分内机制热运行达温自动关机,室温降低后空调器无法启动,降低用户舒适性的问题。针对此问题进行深入研究,分析环境温度检测偏差的原因,提出传感器安装位置改善措施并对其进行实验验证。结果表明,传感器位于远离盘管的空调器右侧可减少温度检测受到的干扰,在室温降低后空调器可正常启动,提高用户舒适性。

Fully Roll‑to‑Roll Processed Efficient Perovskite Solar Cells via Precise Control on the Morphology of PbI_(2):CsI Layer

Perovskite solar cells(PSCs)have attracted tremendous attention as a promising alternative candidate for clean energy generation.Many attempts have been made with various deposition techniques to scale-up manufacturing.Slot-die coating is a robust and facile deposition technique that can be applied in large-area roll-to-roll(R2R)fabrication of thin film solar cells with the advantages of high material utilization,low cost and high throughput.Herein,we demonstrate the encouraging result of PSCs prepared by slot-die coating under ambient environment using a twostep sequential process whereby PbI_(2):CsI is slot-die coated first followed by a subsequent slot-die coating of organic cations containing solution.A porous PbI_(2):CsI film can promote the rapid and complete transformation into perovskite film.The crystallinity and morphology of perovskite films are significantly improved by optimizing nitrogen blowing and controlling substrate temperature.A power conversion efficiency(PCE)of 18.13%is achieved,which is promising for PSCs fabricated by two-step fully slot-die-coated devices.Furthermore,PSCs with a 1 cm2 area yield a champion PCE of 15.10%.Moreover,a PCE of 13.00%is obtained on a flexible substrate by the roll-to-roll(R2R)coating,which is one of the highest reported cells with all layers except for metal electrode fabricated by R2R process under ambient condition.

Facile synthesis of bimetallic N-doped carbon hybrid material for electrochemical nitrogen reduction

Due to the increasingly depleted limited fossil fuel resources,the development of renewable energy is the key to promote sustainable development which is an important part of the energy strategy[1].NH3 is one of most important and largest chemical productions in the world,it can be used as a feedstock for nitrogen fertilizer productions[2,3]or as a carbon-free energy carrier[4,5].

Controllable synthesis of a hollow Cr2O3 electrocatalyst for enhanced nitrogen reduction toward ammonia synthesis

As a fascinating alternative to the energy-intensive Haber-Bosch process,the electrochemically-driven N_(2) reduction reaction(NRR)utilizing the N_(2) and H_(2)O for the production of NH3 has received enormous attention.The development and preparation of promising electrocatalysts are requisite to realize an efficient N_(2) conversion for NH3 production.In this research,we propose a template-assisted strategy to construct the hollow electrocatalyst with controllable morphology.As a paradigm,the hollow Cr_(2)O_(3) nanocatalyst with a uniform size(~170 nm),small cavity and ultrathin shell(~15 nm)is successfully fabricated with this strategy.This promising hollow structure is favourable to trap N_(2) into the cavity,provides abundant active sites to accelerate the three-phase interactions,and facilitates the reactant transfer across the shell.Attributed to these synergetic effects,the designed catalyst displays an outstanding behaviour in N_(2) fixation for NH3 production in ambient condition.In the neutral electrolyte of 0.1 mol·L^(-1) Na_(2)SO_(4),an impressive electrocatalytic performance with the NH3 generation rate of 2.72μg·h^(-1)·cm^(-2) and a high FE of 5.31%is acquired respectively at-0.85 V with the hollow Cr_(2)O_(3) catalyst.Inspired by this work,it is highly expected that this approach could be applied as a universal strategy and extended to fabricating other promising electrocatalysts for realizing highly efficient nitrogen reduction reaction(NRR).

环境温度对骚扰电压和谐波测试结果的影响

选取变频空调、定频空调等不同样品,在不同的环境温度下对其谐波和电源端骚扰电压进行测量,发现谐波值和骚扰电压值随环境温度的变化有很大的不同。电磁兼容工程师对此类设备进行检测时应给予高度的关注。

Oxygen-deficient SnO_(2)nanoparticles with ultrathin carbon shell for efficient electrocatalytic N_(2)reduction

For high-efficiency NH_(3)synthesis via ambient-condition electrohydrogenation of inert N_(2),it is pivotal to ingeniously design an active electrocatalyst with multiple features of abundant surfacial deficiency,good conductivity and large surface area.Here,oxygen-deficient SnO_(2)nanoparticles encapsulated by ultrathin carbon layer(d-SnO_(2)@C)are developed by hydrothermal deposition coupled with annealing process,as promising catalysts for ambient electrocatalytic N_(2)reduction.d-SnO_(2)@C exhibits high activity and excellent selectivity for electrocatalytic conversion of N_(2)to NH_(3)in acidic electrolytes,with Faradic efficiency as high as 12.7%at-0.15 V versus the reversible hydrogen electrode(RHE)and large NH_(3)yield rate of 16.68μg h^(-1)mgcat^(-1)at-0.25 V vs.RHE in 0.1 mol L^(-1)HCl.Benefiting from the structural superiority of enhanced charge transfer efficiency and optimized surface states,d-SnO_(2)@C also achieves excellent long-term stability.

行车空调热工性能测试环境室设计与软件开发

着重探讨了行车空调器热工性能测试系统的主要组成部分之一———环境室的设计方法。参考相关设计标准,并结合行车空调器的结构特点和工作条件,进行了绝热库房结构设计和设备布置、空气处理方案确定、空气处理设备的选择计算等,并完成了调零风机的设计计算和测试软件的编制。所开发的测试系统在某企业行车空调产品热工性能测试的实际应用中达到了设计精度要求。

制冷剂流动方向对微通道蒸发器房间空调器性能影响的对比试验研究

试验研究UF(Upward Flow,制冷剂在微通道蒸发器中自下而上流动)和DF(Downward Flow,制冷剂在微通道蒸发器中自上而下流动)2种制冷剂流动方式下微通道房间空调器的制冷性能,并对其名义制冷工况下制冷剂配液分布进行红外成像.试验结果表明,随着室内空气干球温度的上升,2种方式的制冷量和能效比均不断上升;名义制冷工况下,UF方式优于DF方式,前者的制冷量和能效比EER比后者分别高出21.52%和14.94%;红外成像分析表明,UF方式分液效果优于DF方式.但是,UF方式蒸发器尾部制冷剂分配较少,换热效果下降.

新型制冷剂房间空调器高温特性实验研究

近年来,新型制冷剂R290、R32逐渐应用于家用房间空调器。本文采用同一房间空调器系统(基于R32特性设计),分别对比R290、R32、R22、R410A在不同环境温度下的性能,重点测试并评估了4种制冷剂在极限高温工况下(室外环境温度分别为35、46、52、55℃)的性能衰减特性。结果表明:R22在高温工况下表现最优,R290与R22基本相当,R32高温表现最差;R22与R32在55℃时能力衰减相差3.01%,EER衰减率相差6.03%;R32排气温度与系统压力最高,不适用于高温地区空调的应用。

家用变频空调器低温制冷功能研究

通过对家用变频空调器低环境温度下制冷功能使用场景的调查,分析外部扰动因素与内部扰动因素对家用变频空调器性能和可靠性的影响,给出低温制冷功能开启时制冷系统的控制策略。通过对各种控制参数的合理调节,适时地消除各种扰动因素对制冷循环的干扰,可保证变频空调器高效、安全、稳定运行。