Self-Supporting Nanoporous Copper Film with High Porosity and Broadband Light Absorption for Efficient Solar Steam Generation

Solar steam generation(SSG)is a potential technology for freshwater production,which is expected to address the global water shortage problem.Some noble metals with good photothermal conversion performance have received wide concerns in SSG,while high cost limits their practical applications for water purification.Herein,a self-supporting nanoporous copper(NP-Cu)film was fabricated by one-step dealloying of a specially designed Al_(98)Cu_(2)precursor with a dilute solid solution structure.In-situ and ex-situ characterizations were performed to reveal the phase and microstructure evolutions during dealloying.The NP-Cu film shows a unique three-dimensional bicontinuous ligament-channel structure with high porosity(94.8%),multi scale-channels and nanoscale ligaments(24.2±4.4nm),leading to its strong broadband absorption over the 200–2500 nm wavelength More importantly,the NP-Cu film exhibits excellent SSG performance with high evaporation rate,superior efficiency and good stability.The strong desalination ability of NP-Cu also manifests its potential applications in seawater desalination.The related mechanism has been rationalized based upon the nanoporous network,localized surface plasmon resonance effect and hydrophilicity.

MULTIAXIAL BEHAVIOR OF NANOPOROUS SINGLE CRYSTAL COPPER:A MOLECULAR DYNAMICS STUDY

The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal （MD） method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For a given void volume fraction, apparent size effects in the yield surface are predicted： the smaller behaves stronger. The evolution pattern of defects （i.e., dislocation and stacking faults） is insensitive to the model size and void volume fraction. However, it is loading path dependent. Squared prismatic dislocation loops dominate the incipient yielding under hydrostatic tension while stacking-faults are the primary defects for hydrostatic compression and uniaxial tension/compression.

Effect of heat treatment of Mn-Cu precursors on morphology of dealloyed nanoporous copper

Nanoporous copper with nano-scale pore size was synthesized by dealloying Mn-Cu precursor alloy using a free corrosion method. The effects of heat treatment of Mn-Cu precursors on alloy phase, morphology and composition of the resultant nanoporous copper were investigated. It is revealed that the compositions distribute homogeneously in the bulk Mn-Cu precursors, which consequently results in a more fully dealloying for forming nanoporous copper. The alloy phase changes from Cuo.a9Mno.51 and Cuo.21Mno.79 of non-thermally treated precursor to Cuo.33Mn0.67 of heat treated alloy. The residual Mn content in nanoporous copper is decreased from 12.97% to 2.04% （molar fraction） made from the precursor without and with 95 h heat treatment. The typical pore shape of nanoporous copper prepared by dealloying the precursor without the heat treatment is divided into two different zones： the uniform bi-continuous structure zone and the blurry or no pore structure zone. Nanoporous copper is of a uniform sponge-like morphology made from the heat-treated precursor, and the average ligament diameter is 40 nm, far smaller than that from the non-thermally treated precursor, in which the average ligament diameter is estimated to be about 70 nm.

Adsorption characteristics of copper ion on nanoporous silica

Adsorption by nanoporous media is critically involved in many fundamental geological and geochemical processes including chemical weathering,element migration and enrichment,environmental pollution,etc.Yet,the adsorption behavior of metal ions on nanoporous materials has not been systematically investigated.In this study,MCM-41 material with a monodisperse pore size(4.4 nm)and a large BET specific surface area(839 m^2/g)was hydrothermally prepared and used as a model silica adsorbent to study the adsorption characteristics of Cu^2+as a representative metal ion.The Cu^2+adsorption capacity was found to increase with increasing suspension pH in the range from 3 to 5 and to decrease in the presence of NaNO3.At 25℃,pH=5,and a solid-to-liquid ratio of 5 g/L,the adsorption capacity was determined to be 0.29 mg/g,which can be converted to a dimensionless partition coefficient of 45,indicating a strong enriching effect of nanoporous silica.The adsorption isotherm and kinetic data were fitted to several commonly used thermodynamic,kinetic,and diffusion models.The adsorption mechanism was also studied by Fourier transform infrared spectroscopy,X-ray photoelectron spectroscopy and synchrotron-based X-ray absorption spectroscopy.The results suggest that Cu2+ion adsorption is an entropy-driven endothermal process,possibly involving both outer-sphere and inner-sphere complexes.

Dense copper azide synthesized by in-situ reaction of assembled nanoporous copper microspheres and its initiation performance

Copper azide with high density was successfully synthesized by in-situ reaction of nanoporous copper(NPC)precursor with HN_(3) gaseous.NPC with pore size of about 529 nm has been prepared by electroless plating using polystyrene(PS)as templates.The copper shells thickness of NPC was controlled by adjusting the PS loading amount.The effects of copper shell on the morphology,structure and density of copper azide were investigated.The conversion increased from 87.12%to 95.31%when copper shell thickness decrease from 100 to 50 nm.Meanwhile,the density of copper azide prepared by 529 nm NPC for 24 h was up to 2.38 g/cm^(3).The hollow structure of this NPC was filled by swelling of copper azide which guaranteed enough filling volume for keeping the same shape as well as improving the charge density.Moreover,HNS-IV explosive was successfully initiated by copper azide with minimum charge thickness of 0.55 mm,showing that copper azide prepared has excellent initiation performance,which has more advantages in the application of miniaturized explosive systems.

Eutectic-derived synthesis of hierarchically nanoporous copper for electrochemical actuation and solar steam generation

The utilization of nanoporous copper(np-Cu)as a metallic actuator has gained attention in recent years due to its cost-effectiveness in comparison to other precious metals.Despite this,the enhancement of np-Cu’s actuation performance remains a challenge due to limitations in its strain amplitude and actuation rate.Additionally,np-Cu has been deemed as a promising material for solar absorption due to its localized surface plasmon resonance effect.However,practical applications such as solar steam generators(SSGs)utilizing np-Cu have yet to be documented.In this study,we present the development of hierarchically nanoporous copper(HNC)through the dealloying of a eutectic Al-Cu alloy.The hierarchical structure of the HNC features a combination of ordered flat channels and randomly distributed continuous nanopores,which work in synergy to improve actuation performance.The ordered flat channels,with a sub-micron scale,facilitate rapid mass transport of electrolyte ions,while the nano-sized continuous pores,due to their large specific surface area,enhance the induced strain.Our results indicate that the HNC exhibits improved actuation performance,with a two times increase in both strain amplitude and rate in comparison to other reported np-Cu.Additionally,the HNC,for the first time,showcases excellent solar steam generation capabilities,with an evaporation rate of 1.47 kg·m^(-2)·h^(-1) and a photothermal conversion efficiency of 92%under a light intensity of 1 kW·m^(-2),which rivals that of nanoporous gold and silver film.The enhanced actuation performance and newly discovered solar steam generation properties of the HNC are attributed to its hierarchically porous structure.

Point-defect engineering of nanoporous CuBi_(2)O_(4) photocathode via rapid thermal processing for enhanced photoelectrochemical activity

Engineering point defects such as metal and oxygen vacancies play a crucial role in manipulating the electrical,optical,and catalytic properties of oxide semiconductors for solar water splitting.Herein,we synthesized nanoporous CuBi_(2)O_(4)(np-CBO)photocathodes and engineered their surface point defects via rapid thermal processing(RTP)in controlled atmospheres(O_(2),N_(2),and vacuum).We found that the O_(2)-RTP treatment of np-CBO increased the charge carrier density effectively without hampering the nanoporous morphology,which was attributed to the formation of copper vacancies(VCu).Further analyses revealed that the amounts of oxygen vacancies(Vo)and Cu^(1+)were reduced simultaneously,and the relative electrochemical active surface area increased after the O_(2)-RTP treatment.Notably,the point defects(VC_(u),Cu^(1+),and Vo)regulated np-CBO achieved a superb water-splitting photocurrent density of-1.81 m A cm^(-2) under simulated sunlight illumination,which is attributed to the enhanced charge transport and transfer properties resulting from the regulated surface point defects.Finally,the reversibility of the formation of the point defects was checked by sequential RTP treatments(O_(2)-N_(2)-O_(2)-N_(2)),demonstrating the strong dependence of photocurrent response on the RTP cycles.Conclusively,the surface point defect engineering via RTP treatment in a controlled atmosphere is a rapid and facile strategy to promote charge transport and transfer properties of photoelectrodes for efficient solar water-splitting.

H62铜锌合金在H_(2)SO_(4)腐蚀液中去合金化的过程

以H62黄铜合金带材为原料,通过自由化学腐蚀去合金化法制备具有三维连续孔隙的纳米多孔铜材料。首先将样品进行抛光预处理,然后在60℃的0.5 mol·L^(-1)H_(2)SO_(4)溶液中进行不同时间的自由去合金化处理,研究不同反应时间对合金的去合金化程度、韧带尺寸和相组成的影响。使用扫描电镜、X射线衍射仪、光学显微镜和电化学工作站等表征合金的表面微观形貌、物相组成、显微组织和腐蚀极化曲线。结果表明:随着反应时间的延长,多孔铜的韧带尺寸逐渐变粗,由15 min时的150 nm粗化至60 min时的240 nm,孔隙率逐渐降低;在基体合金中出现纯铜相,合金基体中发生锌的脱出和铜原子的扩散并形成纳米多孔结构;统计韧带尺寸并拟合计算得到韧带粗化系数n为2.325,平均扩散系数Ds为3.117×10^(-15)m^(2)·s^(-1),与相关文献相比具有更快的扩散系数。

Influence of cooling rate and addition of lanthanum and cerium on formation of nanoporous copper by chemical dealloying of Cu_(15)Al_(85) alloy

The influence of cooling rate and addition of La and Ce on the formation of nanoporous copper by chemical dealloying of Cu15Al85 alloy was studied. The components and microstructures of nanoporous copper were characterized by utilizing X-ray diffrac-tion, field emission scanning electron microscopy and energy dispersive X-ray analysis. N2 adsorption/desorption experiments were used to evaluate specific surface areas of samples. The results showed that, with the increase of cooling rate, phase composition of precursor alloy almost had no change, the ligament size of nanoporous copper had a decrease trend, and specific surface area in-creased gradually. And it was found that the specific surface area of the nanoporous copper obtained by Cu15Al85 alloy containing La and Ce was 63.258 m2/g, which was more than 11.739 m2/g compared with the nanoporous copper dealloying by Cu15Al85 alloy without La and Ce under the same conditions.

Relationship between dealloying conditions and coarsening behaviors of nanoporous copper fabricated by dealloying Cu-Ce metallic glasses

Monolithic nanoporous copper （NPC） with tunable ligament size （107-438 nm） was synthesized by dealloying a new Cu-Ce binary glassy precursor in dilute H2 SO4 aqueous solution. The effects of the dealloying conditions on the morphologies of NPC were evaluated comprehensively. The results show that the ligaments of NPC can significantly coarsen with the increase of acid concentration, elevation of reaction temperature or prolongation of immersion time. These coarsening behaviors can be well described by a diffusion based growth kinetic model. Moreover, the surface diffusivity and activation energy for diffu- sion of Cu atoms were also estimated to investigate the formation mechanism of NPC, which is mainly governed by dissolution of Ce element in the glassy precursor coupled with nucleation and growth of Cu clusters via the precursor/solution interface. In the experiment of the degradation of methyl orange （MO） dye, the NPC fabricated by Cu-Ce metallic glasses exhibits superior sono-catalytic activity.2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

Fabrication and Dealloying Behavior of Monolithic Nanoporous Copper Ribbons with Bimodal Channel Size Distributions

Monolithic nanoporous copper （NPC） ribbons with bimodal channel size distributions can be fabricated through chemical dealloying of Mg-32 Cu alloy in an acidic solution at room temperature. The microstructure of the as- dealloyed samples was characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. These NPC ribbons are composed of interconnected large-sized channels （hundreds of nm） with highly porous channel walls （tens of nm）. Both large- and small-sized channels are open, bicontinuous, and interpenetrating. Additionally, it is the first time to find that the evolution process of porous structure along the thickness direction of samples during the dealloying is from the interior to exterior, which is just contrary to the coarsening process along the thickness direction during the post-dealloying. Meanwhile, the corresponding mechanism is discussed in detail.

Morphologies and corrosion resistances of electroless Ni-P coated nanoporous coppers

In order to improve the corrosion resistance of nanoporous coppers （NPCs）, the electroless Ni-P coated NPCs were prepared in plating solutions with different pH values （5, 8, 11） and complexing agent （actic acid, citric acid）. The morphologies and cor- rosion resistances of the as-prepared samples were investigated. The results showed that the double complexing agent com- posed of lactic acid and citric acid is relatively suitable for preparing the Ni-P coated NPC with three-dimensional continuous interpenetrating ligament-channel structures, and the uniform ligaments and nanoporous channels could be obtained at pH8. The Ni-P coated NPC showed higher corrosion potentials than NPC in H2S04, NaOH and NaC1 corrosion solutions.

Effect of thermal oxidation on microstructures and mechanical properties of nanoporous coppers

Nanoporous copper oxides were formed by thermal oxidation of nanoporous copper at 150°C–270°C. The oxidation process of nanoporous copper was investigated by using XRD, SEM, nitrogen adsorption, HRTEM and nanoindentation. The variation of microstructures and mechanical properties was analyzed. The results showed that the content of copper oxides increased, the ligament gradually coarsened, and the mechanical properties of nanoporous structure were improved with the increase of oxidation temperature. When the oxidation temperature was below 210°C, the ligament surface was oxidized to Cu_2O, and the composite structure of Cu_2O@Cu was formed. The formation of CuO occurred since 220°C, and the composite structure of CuO/Cu_2 O@Cu was formed. CuO nanowires were grown on the ligament surface at 250°C; the specific surface area, elastic modulus and hardness of nanoporous structure are 1.37, 3.31 and 7.58 times that of the nanoporous copper, respectively.

Scaling laws and mechanical properties of nanoporous copper

Through molecular dynamics simulations,the mechanical behavior of nanoporous copper under impact loading was investigated with relative densities ranging from 77.91% to 98.36%,focusing on deformation mechanism,the scaling laws and influence of ligament sizes.Results show that the classical Gibson-Ashby′s scaling laws should be modified for prediction of both the Young′s modulus and yield stress.A proportional relationship is established between cell wall thickness and yield stress,and new modified scaling equations are built for nanoporous copper with consideration on both relative mass density and size effects of ligaments.The size effect can be explained by larger surface area/volume ratio of samples with thinner ligament size and limited dislocation source activation due to narrow space between larger numbers of voids.

去合金化制备纳米多孔铜

以Mn-Cu合金为前驱体合金,在0.1 mol/L HCl溶液中自由腐蚀去合金化成功制备出纳米多孔铜,采用扫描电镜和X射线能谱仪对去合金腐蚀前后样品的形貌和成分进行了分析,结果表明,Mn-Cu合金在0.1 mol/L HCl溶液中发生锰的选择性溶解,制备出的纳米多孔铜呈3维网络状均匀结构,平均系带尺寸53 nm,平均孔径尺寸为140 nm。

Mg-Cu合金成分对去合金化制备纳米多孔铜结构的影响

采用感应熔炼与快速凝固法制备Cu含量（原子分数,下同）为33%~67%的Mg-Cu合金薄带,然后通过自腐蚀去合金化法得到纳米多孔铜材料,用X射线衍射仪（XRD）与扫描电镜（SEM）分析多孔铜的相组成和微观形貌,研究Mg-Cu合金成分与腐蚀时间对多孔铜微观结构及形貌的影响。结果表明：Mg-Cu合金中Cu含量为67%时无法形成双连续结构的多孔铜;Cu含量为33%~60%时,形成具有双连续结构的纳米多孔铜,其中Cu含量为50%时,形成均匀、细小的双连续结构纳米多孔铜,平均孔径为60~80 nm,平均系带尺寸为50~80 nm。Mg2Cu相是形成双连续结构的必要条件,而更均匀的双连续结构是由Mg2Cu相和MgCu2相协同去合金化形成的。在含有Mg2Cu相和MgCu2相的Mg-Cu合金腐蚀过程中,Mg2Cu相优先腐蚀,形成腐蚀通道,随后为Mg2Cu相和MgCu2协同腐蚀,最后是残余的MgCu2相腐蚀完全,形成双连续结构纳米多孔铜。

去合金化工艺对纳米多孔铜纯度的影响

采用腐蚀去合金化方法制备纳米多孔铜材料。研究了固溶时间、腐蚀时间及腐蚀温度对纳米多孔铜表面形貌及残余Mn含量的影响。研究表明:由于固溶时间的延长,合金成分越来越均匀化,去合金化后所得纳米多孔铜的残余Mn原子分数降低。固溶95h的前驱体合金,随着腐蚀时间的延长,其残余Mn含量降低不明显;随着温度的升高,其残余Mn原子分数由25℃的3.54%降至60℃的1.14%,但是60℃腐蚀后的孔隙与丝径尺寸明显粗化,样品易碎。通过调整去合金化参数,实验所制备的纳米多孔铜呈现均匀的海绵状纳米多孔结构,残余Mn原子分数1.23%,平均丝径尺寸40nm。

Al-Cu合金成分对去合金化制备纳米多孔铜的影响

采用快速凝固与去合金化相结合的方法制备纳米多孔铜,用XRD、SEM分析样品的相组成和微观形貌,研究前驱体Al-Cu合金成分对纳米多孔铜微观结构及Al2 Cu、AlCu协同性腐蚀的影响。结果表明:Cu原子分数为33%时,去合金化后形成具有双连续结构的纳米多孔铜;Cu原子分数为38%时,形成比表面积更高、更均匀细小的双连续结构纳米多孔铜,平均孔径尺寸约100～150 nm,平均系带尺寸约50～80 nm;Cu原子分数为43%时,形成了双连续结构的纳米多孔铜并在其中分散着纳米颗粒聚集体;Cu原子分数为50%时,形成了纳米颗粒聚集的纳米多孔铜。实验发现,Al2 Cu、AlCu腐蚀的协同作用对双连续结构的形貌有重要的影响。

腐蚀因素对去合金化法制备纳米多孔铜材料结构的影响

采用电弧熔炼与去合金化相结合的方法制备纳米多孔铜.用XRD、SEM分析样品的相组成和微观形貌.研究去合金化中的腐蚀液种类、腐蚀时间以及腐蚀温度等腐蚀环境对纳米多孔铜结构的影响.结果表明:在盐酸溶液中自由腐蚀去合金化可得到孔结构均匀的纳米多孔铜;随着腐蚀时间的延长,孔结构有显著变化,腐蚀3h后得到纳米多孔铜孔结构呈蜂窝状,腐蚀10h后得到双连续结构的纳米多孔铜,随着腐蚀时间的延长,孔径增大且孔壁逐渐粗化;随着温度升高纳米多孔铜双连续结构的孔径逐渐增大,45℃时则形成纳米颗粒聚集的孔结构.通过调整去合金化工艺,厚度约1mm的Mn-Cu薄片在0.3mol/L HCl溶液中,于35℃腐蚀10h得到的纳米多孔铜呈均匀的三维网络状结构,平均孔径尺寸约150nm.

以三维纳米多孔铜膜为集流体锡电极的制备及储锂性能

通过一种新颖的脱合金方法制备厚度为5μm、平均孔径为200~300 nm的三维纳米多孔铜膜，制备过程涉及铜基体上镀锌层的热处理与酸浸过程。以三维纳米多孔铜膜为基体，采用阴极电沉积法制备纳米多孔结构的锡膜电极。应用扫描电子显微镜（SEM）、X 线衍射分析（XRD）和恒流充放电方法对所制备的膜电极的结构与电化学性能进行表征。所制备的多孔锡电极在0.1 C率下的首次充放电中的可逆储锂容量为864 mA·h/g，该容量已接近锡的理论容量（993 mA·h/g）；在50次充放电循环后，可逆容量仍有541 mA·h/g。纳米多孔结构、纳米尺度的锡颗粒及高电子导电性的三维纳米多孔铜膜基体等因素是多孔锡电极显示较好储锂性能的主要原因。