喷涂法制备混合阳离子钙钛矿太阳电池

采用热基底喷涂法分别制备了FA_0.85MA_0.15PbI₃和(FAPbI₃)_0.85(MAPbBr₃)_0.15两种混合阳离子钙钛矿薄膜,对两种薄膜进行了扫描电镜（SEM）、X-射线衍射（XRD）、紫外-可见光吸收光谱（UV-Vis）测试表征。结果表明,该方法制备的混合阳离子钙钛矿薄膜平整致密,FA_0.85MA_0.15PbI₃结晶性更好,并且吸收带边和吸收强度更大。将两种薄膜组装成平板太阳能电池,对电池的光电性能和稳定性进行了分析。结果表明,FA_0.85MA_0.15PbI₃ PSCs光电转换效率为13.21%,(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs光电转换效率为12.08%,并且(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs在放置80 d后,性能基本无变化,表明喷涂法制备(FAPbI₃)_0.85(MAPbBr₃)_0.15 PSCs具有较好的稳定性。     

On the reversibility of hydrogen storage in Ti- and Nb-catalyzed Ca(BH4)2

The hydrogen sorption properties of calcium borohydride (Ca(BH₄)₂) catalyzed with a small amount of TiF₃, TiCl₃, NbF₅ or NbCl₅ are investigated using thermal analyses and X-ray diffraction. NbF₅ exhibits the best performance among all the catalysts; it causes a decrease in the hydrogen desorption temperature which leads to hydrogen absorption at practical temperature and pressure conditions. The hydrogen content of Ca(BH₄)₂ with NbF₅ reaches about 5.0 wt.% after hydrogen absorption at 693 K for 24 h under 90 bar of hydrogen. The main dehydrogenation product of Ca(BH₄)₂ with NbF₅ is a CaH_2−xF_x solid solution with a CaF₂ (C1) structure, while pure Ca(BH₄)₂ produces CaH₂ after hydrogen desorption.     

Improvement of the catalytic properties of Ti-doted Raney-Nickel for H2-Anodes of alkalione fuel cells by Ni(OH)2-surface coating

This paper belongs to a series of three dealing with the latest improvements in the alkaline H₂---O₂ fuel cells operating under mild conditions thanks to their Raney-Ni-catalysts. The first of these papers describes the benefication of a Ni(OH)₂ surface coating on the catalytic activity of Ti-doted Raney-Ni in supported electrodes. This Ni(OH)₂ surface coating is produced by carefully optimized oxidation. A Ni(OH)₂-content of 5 up to 6wt% increases the attainable current density by the factor 3–4. In addition, the exchange current density is markedly enlarged up to a Ni(OH)₂-fraction by 5%, but remains unchanged when further increasing the Ni(OH)₂ percentage. Thus, one may conclude that the Ni(OH)₂ surface coating improves markedly the charge exchange reaction. On the other side, the surface diffusion of H-atoms on the pore walls to the location of charge exchange reaction is hindered by too much Ni(OH)₂.     

Cu(In,Ga)Se2 thin film solar cells with buffer layer alternative to CdS

Progress in fabricating Cu(In,Ga)Se₂ (CIGS) solar cells with ZnS(O,OH) buffer layers prepared by chemical bath deposition (CBD) is discussed in this paper. Such buffer layers could potentially replace CdS in the CIGS solar cell. Total-area conversion efficiency of up to 18.6% has been reported previously using ZnS(O,OH) prepared by CBD. The reported 100 nm CBD ZnS(O,OH) layer was prepared by at least three consecutive depositions, which would make it a relatively expensive replacement for CdS. The recent development of a ZnS(O,OH) layer that enabled to obtain high-efficiency devices using a single-layer CBD is reported in this paper. A 14.4%-efficient device is obtained by using one-layer CBD ZnS(O,OH) on commercial-grade Shell Solar Cu(In,Ga)(S,Se)₂ (CIGSS) absorber and an up to 17.4% device is obtained by using two-layer CBD ZnS(O,OH) on an NREL CIGS absorber.     

Improvement of conversion efficiency by In0.52Al0.48 As window layers for pn InP solar cells

The effects of In_0.52Al_0.48 As window layers on p+n InP cell performances have been experimentally studied. The carrier collection efficiency is improved by introducing the In_0.52Al_0.48 As window layer and the short circuit current density increases. A conversion efficiency of 17.9% is obtained for a heteroface cell with a 50 nm thick window layer, while the efficiency of an InP cell without the window layer is 15.0% under air mass 1.5 condition.     

Thermodynamic assessment of hydrogen production via solar thermochemical cycle based on MoO2/Mo by methane reduction

Inspired by the promising hydrogen production in the solar thermochemical (STC) cycle based on non-stoichiometric oxides and the operation temperature decreasing effect of methane reduction, a high-fuel-selectivity and CH₄-introduced solar thermochemical cycle based on MoO₂/Mo is studied. By performing HSC simulations, the energy upgradation and energy conversion potential under isothermal and non-isothermal operating conditions are compared. In the reduction step, MoO₂: CH₄ = 2 and 1020 K<T_red<1600 K are found to be most favorable for syngas selectivity and methane conversion. Compared to the STC cycle without CH₄, the introduction of methane yields a much higher hydrogen production, especially at the lower temperature range and atmospheric pressure. In the oxidation step, a moderately excessive water is beneficial for energy conversion whether in isothermal or non-isothermal operations, especially at H₂O: Mo= 4. In the whole STC cycle, the maximum non-isothermal and isothermal efficiency can reach 0.417 and 0.391 respectively. In addition, the predicted efficiency of the second cycle is also as high as 0.454 at T_red = 1200 K and T_oxi = 400 K, indicating that MoO₂ could be a new and potential candidate for obtaining solar fuel by methane reduction.     

Novel device structure for Cu(In,Ga)Se2 thin film solar cells using transparent conducting oxide back and front contacts

Cu(In_1−xGa_x)Se₂ (CIGS)-based thin film solar cells fabricated using transparent conducting oxide (TCO) front and back contacts were investigated. The cell performance of substrate-type CIGS devices using TCO back contacts was almost the same as that of conventional CIGS solar cells with metallic Mo back contacts when the CIGS deposition temperatures were below 500 °C for SnO₂:F and 520 °C for ITO. CIGS thin film solar cells fabricated with ITO back contacts had an efficiency of 15.2% without anti-reflection coatings. However, the cell performance deteriorated at deposition temperatures above 520 °C. This is attributed to the increased resistivity of the TCO’s due to the removal of fluorine from SnO₂ or undesirable formation of a Ga₂O₃ thin layer at the CIGS/ITO interface. The formation of Ga₂O₃ was eliminated by inserting an intermediate layer such as Mo between ITO and CIGS. Furthermore, bifacial CIGS thin film solar cells were demonstrated as being one of the applications of semi-transparent CIGS devices. The cell performance of bifacial devices was improved by controlling the thickness of the CIGS absorber layer. Superstrate-type CIGS thin film solar cells with an efficiency of 12.8% were fabricated using a ZnO:Al front contact. Key techniques include the use of a graded band gap Cu(In,Ga)₃Se₅ phase absorber layer and a ZnO buffer layer along with the inclusion of Na₂S during CIGS deposition.     

石墨烯包封Na3V2(PO4)3用作钠离子电池负极材料的电化学性能探究

具有三维网络结构的NASICON型Na₃V₂(PO₄)₃材料,由于其稳定的电压平台,较高的理论容量（117 mA∙h/g),被视为一种具有良好应用前景的钠离子电池负极材料。采用溶剂热和进一步热处理的方式,获得石墨烯包封Na₃V₂(PO₄)₃的复合材料[Na₃V₂(PO₄)₃/G],有效提高了Na₃V₂(PO₄)₃的电子导电性。在0.01 ~ 3.00 V电压区间,0.2 C倍率进行测试时,Na₃V₂(PO₄)₃/G复合材料在230圈循环后,其放电比容量保持在100.9 mA∙h/g,容量保持率高达68.4%,即使在5 C倍率,其放电比容量仍可达65.2 mA∙h/g。然而,纯相Na₃V₂(PO₄)₃的放电比容量仅为47.4 mA∙h/g,容量保持率仅为44.7%,在5 C倍率时,其放电比容量仅为25.1 mA∙h/g,证实石墨烯包封结构能显著提升Na₃V₂(PO₄)₃的循环稳定性和倍率性能。     

XPS analysis of CdS/CuInSe2 heterojunctions

CdS/CuInSe₂ (CIS) heterojunctions were investigated by XPS analysis. An In-excess layer which may form an ordered vacancy compound (OVC) was present at the as-deposited CIS surface and it remained after chemical bath deposition of a CdS layer. The In-excess layer was removed by preferential etching with NH₃ aqueous solution. This result implies that the surface of the as-deposited CIS film was converted from the OVC with n-type conductivity into the CIS with p-type by NH₃ treatment. The conduction band offsets at the CdS/p-CIS and CdS/n-OVC were determined to be 1.0 and 0.3 eV, respectively. The CIS solar cells fabricated with n-OVC surface layer exhibited higher cell efficiencies than those fabricated with p-CIS surface layer.     

锑基硫属化合物半导体及太阳电池

锑基硫属化合物是一类性质稳定、环境友好、元素含量丰富、带隙连续可调、光电性质优异的半导体材料,包括硒化锑（Sb₂Se₃）、硫化锑（Sb₂S₃）以及硒硫化锑[Sb₂(S,Se)₃]等。其中,Sb₂(S,Se)₃的带隙和太阳光谱的匹配度较高,比较适合作为太阳电池的光吸收层材料。以Sb₂(S,Se)₃为光吸收层的太阳电池取得了10% 的认证能量转换效率,显示了锑基硫属化合物太阳电池的巨大潜力。本文详细阐述了锑基硫属化合物的材料及光电特性、薄膜制备工艺及缺陷特性。结合近年来锑基硫属化合物太阳电池的研究进展,提出进一步提高锑基硫属化合物太阳电池性能的方向和策略。     

Effects of catalysts doping on the thermal decomposition behavior of Zn(BH4)2

Transition metal complex borohydrides, Zn(BH₄)₂ have been synthesized by solid-state mechanochemical process. Various catalysts such as TiCl₃, TiF₃, nanoNi, nanoFe, Ti, nanoTi, and Zn were used to dope the borohydride in order to lower the decomposition temperature in the range of , without a significant reduction in the hydrogen content per total weight of the sample. In addition, the structural, bonding and thermal characteristics of undoped and catalysts doped Zn(BH₄)₂ were compared and analyzed to find out the optimum catalyst and dopant concentration. Among the different catalysts, 1.5 mol% of nanoNi obtained from Quantum Sphere Inc. was found to possess the optimum behavior in terms of fast kinetics and lowering the melting and decomposition temperature of Zn(BH₄)₂.     

Decoration of vertically aligned TiO2 nanotube arrays with WO3 particles for hydrogen fuel production

WO₃ decorated photoelectrodes of titanium nanotube arrays (W-oxide TNTAs) were synthesized via a two-step process, namely, electrochemical oxidation of titanium foil and electrodeposition of W-oxide for various interval times of 1, 2, 3, 5, and 20 min to improve the photoelectrochemical performance and the amount of hydrogen generated. The synthesized photoelectrodes were characterized by various characterization techniques. The presence of tungsten in the modified TNTAs was confirmed using energy dispersive X-ray spectroscopy (EDX). Field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscope (HRTEM) proved the deposition of W-oxide as small particles staked up on the surface of the tubes at lower deposition time whereas longer times produced large and aggregate particles to mostly cover the surface of TiO₂ nanotubes. Additionally, the incorporation of WO₃ resulted in a shift of the absorption edge toward visible light as confirmed by UV-Vis diffuse reflectance spectroscopy and a decrease in the estimated band gap energy values hence, modified TNTAs facilitated a more efficient utilization of solar light for water splitting. From the photoelectrochemical measurement data, the optimal photoelectrode produced after 2 min of deposition time improved the photo conversion efficiency and the hydrogen generation by 30% compared to that of the pure TNTA.     

Roles of various Ni species on TiO2 in enhancing photocatalytic H2 evolution

Low-cost nickels can be used as cocatalyst to improve the performance of photocatalysts, which may be promising materials applied in the field of photocatalytic water splitting. In this study, different nickel species Ni, Ni(OH)₂, NiO, NiO_x, and NiS are used to modified titanium dioxide (P25) to investigate their roles on the photocatalytic hydrogen evolution activities. UV-visible, X-ray diffraction (XRD), Brunner-Emmet-Teller (BET) measurements, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) analysis etc. are employed to characterize the physical and chemical properties of catalysts. The results indicate that all the nickel species can improve the photocatalytic hydrogen production activity of P25. The P25 modified with NiO_x and NiS has more superior photocatalytic hydrogen evolution activities than those modified with other nickel species. The reason for this is that NiO_x and NiS can form p-n junctions with P25 respectively. In addition, NiO_x can be selectively deposited on the active sites of P25 via in situ the photodeposition method and NiS is beneficial for H⁺ reacting with photo-excited electrons.     

Ag/Al2O3(Li2O)/g-C3N4光催化乙醇制取环氧乙烷

本文制备了一系列Ag/Al₂O₃(Li₂O)/g-C₃N₄复合催化剂,考察了其可见光催化乙醇制取环氧乙烷的性能。Li₂O可调变Al₂O₃表面的酸性,从而降低了主要副产物乙醛的选择性。Ag/Al₂O₃(Li₂O) 在g-C₃N₄上的负载量对产物环氧乙烷的选择性有较大影响,当Ag/Al₂O₃(Li₂O) 负载量为5wt%时,乙醇具有较高的转换率,且环氧乙烷的选择性高达100%。     

Hydrogen production by biomass gasification in supercritical or subcritical water with Raney-Ni and other catalysts

Gasification of peanut shell, sawdust and straw in supercritical or subcritical water has been studied in a batch reactor with the presence of a series of Raney-Ni and its mixture with ZnCl₂ or Ca(OH)₂. The main gas products were hydrogen, methane, carbon dioxide, and a small amount of carbon monoxide. Different types of Raney-Ni, containing different metal components such as Fe, Mo or Cr, have different influences on the gasification yield and hydrogen selectivity. The catalysis effect can be improved obviously by adding ZnCl₂ or Ca(OH)₂. Increasing the reaction temperature or adding ZnCl₂ and Ca(OH)₂ could improve the mass of H₂ in gas products and reduce the mass of CH₄ and CO₂ at the same time. The possible mechanism is that ZnCl₂ can decompose the biomass particle by accelerating cellulose hydrolyzation in high-temperature water, increasing more specific surface to admit catalysts, while Ca(OH)₂ can absorb CO₂ to produce CaCO₃ deposit, which can drop out from the reactant system, and which will drive the reaction to get more hydrogen. With respect to the biomass conversion to gas product and selectivity of H₂ at low temperature, the series of Raney-Ni has shown many advantages over other catalysts; thus, this kind of catalyst has great potential to be utilized in the hydrogen industry for the gasification of biomass.     

The electrochromic properties of hydrated nickel oxide films formed by colloidal and anodic deposition

Hydrated nickel oxide NiO_xH_y films were deposited onto indium tin oxide (ITO) coated glass by two methods (i) colloidal precipitation and (ii) anodic electrodeposition. The electrochromic properties of hydrated nickel oxide films were studied by transmittance measurements (UV/VIS/NIR), and Fourier transform infrared reflectance spectroscopy as a function of the key deposition parameters. The solar transmittance was calculated for films switched in both bleached and coloured states. The best results were achieved for films produced by anodic electrodeposition from stable solutions with solar transmittance T_s(bleached) = 0.82 and T_s(coloured) = 0.22. Corresponding optimum values for the films produced by colloidal precipitation were solar transmittance T_s(bleached = 0.82 and T_s(coloured) = 0.47. Fourier transform spectrophotometry was used for elucidating changes in hydration, hydroxylation and for the characterization of structural characteristics in the bleached and coloured states. It was found that free OH stretching vibration at 3647 cm⁻¹ corresponds to Ni(OH)₂ for both anodic and colloidal deposited films in the reduced (bleached) state. In the oxidised state hydrogen bonded OH at 3360 cm⁻¹ is observed.     

Capacitive performance and cycling stability of NixCo1-x(OH)2 xerogels

研究了Ni_xCo_1-x(OH)₂干凝胶中钴含量对其电性能及循环稳定性的影响。用溶胶-凝胶法制备了Ni_xCo_1-x(OH)₂干凝胶材料,用液氮吸附、XPS和XRD研究了含钴Ni(OH)₂干凝胶的组成和结构,用恒电流技术研究了它们的电容性能。结果表明,Ni_xCo_1-x(OH)₂干凝胶具有较高的比表面积和丰富的中孔;添加钴改善了Ni_xCo_1-x(OH)₂干凝胶的倍率性能,当钴含量达到24%时效果最佳;充放电后Co_xNi_1-x(OH)₂干凝胶的晶态结构仍是β-Ni(OH)₂晶相结构,钴含量20%以上的Co_xNi_1-x(OH)₂干凝胶充放电后微晶尺寸变化不明显;组成的活性炭/ Ni_0.76Co_0.24(OH)₂干凝胶电容器20 mA/cm²充放电循环时,库仑效率达到95%以上,循环100000次以上,电容器的比容量仍保持在90%以上。在长循环过程中,Ni_0.76Co_0.24(OH)₂干凝胶的微晶尺寸变化不大,微晶晶胞a轴逐渐变大、c轴逐渐缩小,晶胞参数趋向理想的β-Ni(OH)₂晶体。     

纳米多孔碳对MgO/Mg(OH)2化学蓄热性能影响的实验研究

为提高MgO/Mg(OH)₂的热化学蓄/放热性能,采用焙烧法将氧化镁（MgO）负载在纳米多孔碳（NCP）材料上制备纳米碳基氧化镁（NCP-MgO）复合材料。研究结果表明,NCP载体使MgO在其表面形成粒径为10 ~ 30 nm大小的颗粒,复合材料NCP-MgO具有较高的导热系数,负载80% MgO后导热系数是纯MgO的2.6倍。在反应温度110℃、水蒸气压力57.8 kPa的实验工况下,发现水合速率的大幅提升是强化MgO/Mg(OH)₂蓄热性能的主要原因,在水合反应60 min和120 min时,NCP-MgO复合材料的水合转化率分别是纯MgO的2.25倍和1.6倍。在水合反应120 min后,MgO负载率为80%的NCP-MgO复合材料的蓄热密度可达1 053 kJ/kg,是纯MgO的1.4倍。该研究可为MgO/Mg(OH)₂在化学蓄热系统的应用提供一定的参考。     

In situ grown TiN/N-TiO2 composite for enhanced photocatalytic H2 evolution activity

Titanium nitride (TiN) decorated N-doped titania (N-TiO₂) composite (TiN/N-TiO₂) is fabricated via an in situ nitridation using a hydrothermally synthesized TiO₂ and melamine (MA) as raw materials. After the optimization of the reaction condition, the resultant TiN/N-TiO₂ composite delivers a hydrogen evolution activity of up to 703 μmol/h under the full spectrum irradiation of Xe-lamp, which is approximately 2.6 and 32.0 times more than that of TiO₂ and TiN alone, respectively. To explore the underlying photocatalytic mechanism, the crystal phase, morphology, light absorption, energy band structure, element composition, and electrochemical behavior of the composite material are characterized and analyzed. The results indicate that the superior activity is mainly caused by the in situ formation of plasmonic TiN and N-TiO₂ with intimate interface contact, which not only extends the spectral response range, but also accelerates the transfer and separation of the photoexcited hot charge carrier of TiN. The present study provides a fascinating approach to in situ forming nonmetallic plasmonic material/N-doped TiO₂ composite photocatalysts for high-efficiency water splitting.     

Preparation and electrochemical characteristics of LiNi1/3Mn1/3Co1/3O2 coated with metal oxides coating

LiNi_1/3Mn_1/3Co_1/3O₂ prepared by a spray drying method exhibited poor cyclic performance when it was operated at rates of 0.5C and 2C in 3–4.6 V. A metal oxide (ZrO₂, TiO₂, and Al₂O₃) coating (3 wt%) could effectively improve its cyclic performance at both 0.5C and 2C. Electrochemical impedance spectroscopy (EIS) studies suggested that both the surface resistance and the charge transfer resistance of the bare LiNi_1/3Mn_1/3Co_1/3O₂ significantly increase after 100 cycles, whose origin is mainly related to the change in both the particle surface and electrode morphologies. The presence of a thin metal oxide layer could remarkably suppress the increase in the total resistance (sum of the surface resistance and the charge transfer resistance), which was attributed to the improvement in good cyclic performances.