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排序方式: 共有196条查询结果,搜索用时 31 毫秒
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CoOx改性TiO2光催化剂的制备、优化及其光催化分解水析氢性能研究 总被引:4,自引:0,他引:4
利用热分解法制备了不同掺杂量的CoOx-TiO2系列光催化剂, 并优化了制备方法。在用XRD、TEM和XPS等技术对催化剂表征的基础上,探讨了乙醇作为电子给体时CoOx改性对P25-TiO2光催化分解水析氢性能的影响。本文还利用连续瞬态电流-时间响应和循环伏安法等电化学方法,考察了CoOx-TiO2改性系列光催化剂光照条件下电流响应强度、起始光电响应特性差别及光催化析氢电位变化等光电化学性能。光催化性能实验结果表明,适当掺杂CoOx(110~400 ℃焙烧时最佳掺杂量约为0.4wt% Co,500 ℃焙烧时最佳掺杂量约为0.6~0.8wt% Co)能够显著地提高TiO2析氢光催化性能,产氢速率提高2个数量级。另外在适当温度下的热处理,能够改善催化剂光催化性能(最佳处理温度为300~400 ℃)。光电化学性能评价结果表明,适当掺杂CoOx和适当温度下焙烧能在催化剂表面形成较多的析氢活性物种——含钴复合物,能有效增强催化剂光电流响应强度,并使得析氢光还原电位向有利于析氢方向位移。高含量掺杂CoOx会在催化剂表面形成某种碳化物物种,大量含钴复合物活性中心的出现会降低光吸收效率,增加TiO2表面光生电子-空穴复合率而使催化剂失去析氢光催化性能。 相似文献
3.
Yu.?V.?PleskovEmail author M.?D.?Krotova V.?G.?Ralchenko A.?V.?Khomich R.?A.?Khmelnitskii 《Russian Journal of Electrochemistry》2005,41(3):304-309
The photocurrent and photopotential for undoped polycrystalline diamond film electrodes prepared by chemical vapor deposition and annealed in vacuum at 1500–1640°C are measured. The metal-like samples (annealed at 1630°C) have a negligible photosensitivity. Judging from the positive sign of the photopotential and the cathodic direction of the photocurrent, the material under study formally behaves as a p-type semiconductor. The photoeffects are presumably caused by structure defects, in particular, the dislocations in diamond crystallites formed close to intercrystalline boundaries during the high-temperature annealing.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 343–349.Original Russian Text Copyright © 2005 by Pleskov, Krotova, Ralchenko, Khomich, Khmelnitskii. 相似文献
4.
用光电流作用谱、光电流-电势图等光电化学方法研究了ITO(铟锡氧化物导电玻璃)/TiO2 /Q-PbS(量子点PbS)膜电极的光电转换性质。结果表明,由于量子尺寸的效应,在膜电极制备中,随着ITO/TiO2电极在饱和Pb(CH3COO)2溶液中浸泡时间的不同,所制备的Q-PbS颗粒大小不同,禁带宽度随着浸泡时间的增大而减小,浸泡时间为40 s、在80 ℃烘干下制备的Q-PbS的禁带宽度为1.68 eV,其价带位置为-5.072 eV。Q-PbS修饰ITO/TiO2电极可使光电流发生明显的红移,从而提高宽禁带半导体的光电转换效率。 相似文献
5.
Lili Hu Marcus Wolf Michael Grätzel Zhonghong Jiang 《Journal of Sol-Gel Science and Technology》1995,5(3):219-226
The hydrolysis of niobium pentaethoxide precursor in the presence of triethylamine (TEA) is discussed. Three precursors with TEA/Nb(OEt)5 mole ratios of 0.25, 0.4 and 0.8 were prepared. Niobia colloids with different appearance were obtained after autoclaving the above precursors at 250°C during 12 h. The surface roughness and microstructure of niobia films prepared with the colloids by spread coating method are strongly dependent on the TEA/Nb(OEt)5 mole ratio. At a value of 0.4 TEA/Nb(OEt)5 mole ratio, a niobia film with large surface roughness can be achieved. It is opaque and mechanically stable and has differently ordered needle microstructure. The crystalline structure and photoelectrochemical property of niobia film with the largest surface roughness were examined. The effect of CO2 gas bubbling, reflux and addition of 2-methoxyethanol on the hydrolysis of Nb(OEt)5 and the nature of the Nb2O5 films is also discussed. 相似文献
6.
Yasuhiro Tachibana Ryusuke Muramoto Hajime Matsumoto Susumu Kuwabata 《Research on Chemical Intermediates》2006,32(5):575-583
We investigated the photoelectrochemical characteristics and photo-stability of Cu2O layered on a copper plate using a hydrophobic ionic liquid. Our findings revealed that Cu2O is stable under white light irradiation, provided water is removed from the electrolyte. Methyl viologen derivative, a well-established
electron acceptor, was introduced to the ionic liquid electrolyte, allowing the photo-induced electron transfer reaction at
the Cu2O/electrolyte interface to be characterized. The methyl viologen derivative exhibited two distinct redox reactions at −0.56
V and −0.98 V vs. Ag/AgCl, clearly indicating that no dimer formation or co-proportionation reaction occurred. The excessive photocurrents
being continuously generated resulted from a viable photo-induced electron transfer reaction from the Cu2O to the acceptor. However, in contrast, the reduction of the Cu2O by water in the aqueous solution causes this electron transfer to be inhibited. We further demonstrate that these findings
are vital to understanding the role of the Cu2O and its photoelectrochemical applications. 相似文献
7.
Dr. Yangchun Lan Dr. Shuai Kang Dr. Dehu Cui Zhuofeng Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):4089-4097
Hematite nanoarrays are important photoanode materials. However, they suffer from serious problems of charge transfer and surface states; in particular, the surface states hinder the increase in photocurrent. A previous strategy to suppress the surface state is the deposition of an Fe-free metal oxide overlayer. Herein, from the viewpoint of atomic bonding energy, it is found that the strength of bonding around Fe atoms in the hematite is the key to suppressing the surface states. By treating the surface of hematite with Se and NaBH4, the Fe2O3 transforms to a double-layer nanostructure. In the outer layer, the Fe−O bonding is reinforced and the Fe−Se bonding is even stronger. Therefore, the surface states are inhibited and the increase in the photocurrent density becomes much faster. Besides, the treatment constructs a nanoscale p–n junction to promote the charge transfer. Improvements are achieved in onset potential (0.25 V shift) and in photocurrent density (5.8 times). This work pinpoints the key to suppressing the surface states and preparing a high-efficiency hematite nanoarray, and deepens our understanding of hematite photoanodes. 相似文献
8.
Enhancement of Solar Hydrogen Evolution from Water by Surface Modification with CdS and TiO2 on Porous CuInS2 Photocathodes Prepared by an Electrodeposition–Sulfurization Method
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Dr. Jiao Zhao Dr. Tsutomu Minegishi Li Zhang Dr. Miao Zhong Gunawan Dr. Mamiko Nakabayashi Dr. Guijun Ma Dr. Takashi Hisatomi Dr. Masao Katayama Prof. Dr. Shigeru Ikeda Prof. Dr. Naoya Shibata Prof. Dr. Taro Yamada Prof. Dr. Kazunari Domen 《Angewandte Chemie (International ed. in English)》2014,53(44):11808-11812
Porous films of p‐type CuInS2, prepared by sulfurization of electrodeposited metals, are surface‐modified with thin layers of CdS and TiO2. This specific porous electrode evolved H2 from photoelectrochemical water reduction under simulated sunlight. Modification with thin n‐type CdS and TiO2 layers significantly increased the cathodic photocurrent and onset potential through the formation of a p–n junction on the surface. The modified photocathodes showed a relatively high efficiency and stable H2 production under the present reaction conditions. 相似文献
9.
Jin Su Takashi Hisatomi Tsutomu Minegishi Kazunari Domen 《Angewandte Chemie (International ed. in English)》2020,59(33):13800-13806
Most CdTe photoanodes and photocathodes show positive and negative photocurrent onset potentials for water oxidation and reduction, respectively, and are thus unable to drive photoelectrochemical (PEC) water splitting without external applied biases. Herein, the activity of a CdTe photoanode having an internal p‐n junction during PEC water oxidation was enhanced by applying a CdCl2 annealing treatment together with surface modifications. The resulting CdTe photoanode generated photocurrents of 1.8 and 5.4 mA cm?2 at 0.6 and 1.2 VRHE, respectively, with a photoanodic current onset potential of 0.22 VRHE under simulated sunlight (AM 1.5G). The CdCl2 annealing increased the grain sizes and lowered the density of grain boundaries, allowing more efficient charge separation. Consequently, a two‐electrode tandem PEC cell comprising a CdTe‐based photoanode and photocathode split water without any external bias at a solar‐to‐hydrogen conversion efficiency of 0.51 % at the beginning of the reaction. 相似文献
10.
Pin Xu Peng‐Yu Chen Hai‐Chao Xu 《Angewandte Chemie (International ed. in English)》2020,59(34):14275-14280
Heteroarenes are structural motifs found in many bioactive compounds and functional materials. Dehydrogenative cross‐coupling of heteroarenes with aliphatic C?H bonds provides straightforward access to functionalized heteroarenes from readily available materials. Established methods employ stoichiometric chemical oxidants under conditions of heating or light irradiation. By merging electrochemistry and photochemistry, we have achieved efficient photoelectrochemical dehydrogenative cross‐coupling of heteroarenes and C(sp3)?H donors through H2 evolution, without the addition of metal catalysts or chemical oxidants. Mechanistically, the C(sp3)?H donor is converted to a nucleophilic carbon radical through H‐atom transfer with chlorine atom, which is produced by light irradiation of anodically generated Cl2 from Cl?. The carbon radical then undergoes radical substitution to the heteroarene to afford alkylated heteroarene products. 相似文献