CdS Reinforced with CoSX/NiCo-LDH Core-shell Co-catalyst Demonstrate High Photocatalytic Hydrogen Evolution and Durability in Anhydrous Ethanol

At present, inefficient charge separation of single photocatalyst impedes the development of photocatalytic hydrogen evolution. In this work, the CoS_X/NiCo-LDH core-shell co-catalyst was cleverly designed, which exhibit high activity and high stability of hydrogen evolution in anhydrous ethanol system when coupled with CdS. Under visible light (λ≥420 nm) irradiation, the 3 %Co/NiCo/CdS composite photocatalyst exhibits a surprisingly high photocatalytic hydrogen evolution rate of 20.67 mmol g⁻¹ h⁻¹, which is 59 times than that of the original CdS. Continuous light for 20 h still showed good cycle stability. In addition, the 3 %Co/NiCo/CdS composite catalyst also shows good hydrogen evolution performance under the Na₂S/Na₂SO₃ and lactic acid system. The fluorescence (PL), ultraviolet-visible diffuse reflectance (UV-vis) and photoelectrochemical tests show that the coupling of CdS and CoS_X/NiCo-LDH not only accelerates the effective transfer of charges, but also greatly increases the absorption range of CdS to visible light. Therefore, the hydrogen evolution activity of the composite photocatalyst has been significantly improved. This work will provide new insights for the construction of new co-catalysts and the development of composite catalysts for hydrogen evolution in multiple systems.     

表面缺陷与钯的沉积对硫化镉纳米晶粒的光催化制氢性能的影响

The development of the photocatalytic production of hydrogen from water splitting has attracted immense attention in recent years. CdS is a potential photocatalyst with a visible light response, though it still suffers from a limited activity for hydrogen production due to the fast recombination of photo-induced electron/hole pairs and the low reaction rate of hydrogen evolution on the surface. Studies on the effect of CdS surface structure and properties on hydrogen production are still very limited. In this work, we prepared three CdS nanocrystals with different morphologies: long rod, short rod, and triangular plate. The prepared samples were well characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area analysis, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). From the results of TEM, XRD and XPS, we find that the three CdS nanocrystals with different morphologies were successfully synthesized. From the PL spectra, we conclude that the area of exposed nonpolar surface and degree of surface defects increase with an increase in aspect ratio. We also performed the photocatalytic hydrogen production reaction using the three CdS crystals. Long rod-like CdS (lr-CdS) exhibits the highest photocatalytic activity, with a hydrogen production rate of 482 μmol·h^-1·g^-1, which is 2.6 times that of short rod-like CdS (sr-CdS) (183 μmol·h^-1·g^-1) and 8.8 times that of triangular plate-like CdS (tp-CdS, 55 μmol h^-1·g^-1). It is found that lr-CdS shows a higher hydrogen production rate than sr-CdS and tp-CdS. We find that the hydrogen production rate is related to the degree of surface defects. Surface defects can trap the photo-induced electrons/holes, thus decreasing their probability of recombination. In addition, these defects can be used to anchor Pd particles to form a heterojunction structure that facilitates the separation of photo-induced charges. Therefore, we also compared three CdS/Pd nanocrystals synthesized with the three abovementioned morphologies with respect to hydrogen production. With 1% (w, mass fraction) Pd, the hydrogen production rate was greatly enhanced compared to all the CdS catalysts. Compared to the unpromoted CdS, the reaction rate is enhanced 43.1, 10.7 and 6.0 times over those of sr-CdS, lr-CdS and tp-CdS, respectively. Notably, the hydrogen production rate with short rod-like CdS/Pd reaches 7884 μmol·h^-1·g^-1, which can be favorably compared with the ever-increasing values reported in the literature. Hopefully, this work provides knowledge on the effect of crystal surface structure and properties on photocatalysis.     

硫化镉纳米晶的表面缺陷及钯修饰对光催化制氢性能的影响

<正>化石能源的过度消耗以及由此带来的环境问题日渐突出,开发利用可再生新能源迫在眉睫,近年来氢气被认为是一种清洁替代能源。自从发现利用TiO_2光催化分解水制氢(PHER)~1以来,半导体光催化剂制氢技术的开发已经受到人们的极大关注~(2,3)。金属硫化物(这里主要指ds区和p区金属)一般拥有较窄的带宽以及合适的导带位     

含氧空位缺陷钨酸铋光催化产氢性能研究

新型半导体光催化剂钨酸铋是目前研究广泛的光催化剂,但因其电子空穴对易复合的问题,限制了光催化产氢性能。为解决这一问题,采用锂-乙二胺溶液在钨酸铋表面构筑可控氧空位缺陷和金属缺陷。通过材料表征对比了钨酸铋经锂-乙二胺处理前后的变化,并对两者进行了产氢速率测试。钨酸铋在经过锂-乙二胺处理过后产生了氧空位缺陷和降价的金属中心,材料颜色从原先的黄白色转变为黄棕色,增强了光吸收能力。颗粒的主体结构以及物质成分并未发生变化,仍保持花球状颗粒结构,但处理后钨酸铋颗粒表面原先的光滑的片状结构变得粗糙,且方形纳米薄片锋利边缘变光滑,提高了光催化反应面积。这些变化使锂-乙二胺处理后的钨酸铋光催化产氢性能相比未处理之前得到了一定的提升。     

Performance and Mechanism Research of Au-HSTiO_2 on Photocatalytic Hydrogen Production

In this paper, we report our attempts to raise the efficiency of liquid reduction method when using high specific surface area TiO_2(HSTiO_2) by doping Au. Characterization of Au-HSTiO_2 was conducted via XRD, UV-vis, SEM, and photocurrent intensity. The experimental results show that Au-HSTiO_2 exhibits prominently higher photocatalytic hydrogen production than TiO_2 and HSTiO_2. Enhanced photosynthetic hydrogen production ability of Au-HSTiO_2 should be attributed to the presence of abundant surface active sites of HSTiO_2, remarkably extending electronic holes in Au doping. This study provides a promising photosynthetic material for hydrogen production.     

Functionalized Membranes for Photocatalytic Hydrogen Production

Functionalized vesicles for photocatalytic hydrogen production in water have been prepared by co‐embedding of amphiphilic photosensitizers and a hydrogen‐evolving catalyst in phospholipid membranes. The self‐assembly allows a simple two‐dimensional arrangement of the multicomponent system with close spatial proximity, which gave turnover numbers up to 165 for the incorporated amphiphilic cobaloxime water reduction catalyst 3 b under optimized conditions in purely aqueous solution. Superior photocatalytic activity in fluid membranes indicates that mobility and dynamic reorganization of catalytic subunits in the membrane promote the visible‐light‐driven hydrogen production. The functionalized membranes represent nanostructured assemblies for hydrogen production in aqueous solution mimicking natural photosynthesis.     

超声驱动制备Au/CdS催化剂及其高效光催化产氢北大核心CSCD

以HAuCl_(4)为前驱体,采用一种简单、快速的超声驱动法,在甲醇溶液中形成Au纳米粒子并沉积在CdS基底上合成Au/CdS,用于光催化分解水产氢.结果表明:当沉积Au的含量达到1.0%(质量分数)时,Au/CdS的产氢活性显著增强,可达到6.7 mmol·g^(-1) ·h^(-1) ,是纯CdS的21.6倍.超声驱动可在甲醇溶液中有效将前驱体(HAuCl_(4))中的Au3+还原为Au纳米粒子,并与CdS表面紧密作用,提高了光生电荷的分离效率,实现了高效光催化产氢.有关结果为快速、有效制备光催化产氢性能较好的金属/半导体催化剂提供了新的方法.     

Pd增强缺陷态TiO2纳米管阵列的光催化产氢性能

通过光还原沉积法, 利用氧空位诱导作用, 在Ni掺杂的缺陷态TiO₂纳米管阵列(TNT-Ni)上得到金属 Pd含量不同的Pd-TNT-Ni催化剂. 采用场发射扫描电子显微镜(SEM)、 X射线光电子能谱(XPS)、 紫外-可见 漫反射(UV-Vis DRS)、 表面光电压(SPV)、 光致发光光谱(PL)和电化学测试等表征手段, 探究了Pd与Ni掺杂的缺陷态TiO₂纳米管阵列之间的强相互作用对其光吸收特性和载流子分离及传输效率的影响, 阐明了强相互 作用对材料光催化活性的调控机理, 提出了Pd增强Pd-TNT-Ni光催化性能的作用机理. 结果表明, 通过光还 原法制备的Pd纳米颗粒尺寸为10~20 nm的Pd₁₂₀-TNT-Ni样品的光响应值为4.22 mA/cm², 是未负载Pd样品光 响应值(1.14 mA/cm²)的3.7倍, 其具有最佳的平均产氢速率(5.16 mmol·g^?1·h^?1), 是TNT样品平均产氢速率 (0.45 mmol·g^?1·h^?1)的12倍, 表明Pd与缺陷态TiO₂纳米管阵列之间的强相互作用驱动了载流子的分离及传输, 且Pd作为电子捕获势阱及反应活性位点, 显著提高了材料的光催化性能.     

Hydrogen Production on a Hybrid Photocatalytic System Composed of Ultrathin CdS Nanosheets and a Molecular Nickel Complex

The production of clean and renewable hydrogen through water splitting by using solar energy has received much attention due to the increasing global energy demand. We report an economic and artificial photosynthetic system free of noble metals, consisting of ultrathin CdS nanosheets as a photosensitizer and nickel‐based complex as a molecular catalyst. Emission quenching and flash photolysis studies reveal that this hybrid system allows for effective electron transfer from the excited CdS nanosheets to the nickel‐based complex to generate reduced intermediate species for efficient hydrogen evolution. Notably, the unique morphological and structural features of the ultrathin CdS nanosheets contribute to the highly efficient photocatalytic performance. As a consequence, the resulting system shows exceptional activity and stability for photocatalytic hydrogen evolution in aqueous solution with a turnover number (TON) of about 28 000 versus catalyst and a lifetime of over 90 h under visible light irradiation.     

类石墨烯C3N4纳米片光催化分解水制氢中的量子限域效应

从层状化合物获得的纳米片是一类新型纳米结构材料,这种二维各向异性的纳米甚至亚纳米级的材料具有独特的物理化学性能,其中最好的一个例证就是从石墨烯C₃N₄到石墨烯C₃N₄纳米片的转变。通过高温氧化热刻蚀方法将体相g-C₃N₄剥离成g-C₃N₄纳米片,应用于染料敏化可见光分解水产氢,表现出了较体相g-C₃N₄高于2.6倍的产氢速率。通过X射线衍射（XRD）、傅里叶变换红外（FTIR）光谱、扫描电子显微镜（SEM）、Brunauer-Emmett-Teller（BET）、荧光光谱和光电化学等表征研究了g-C₃N₄纳米片的结构及曙红（EY）和g-C₃N₄纳米片之间的电子迁移过程。热剥离后的g-C₃N₄纳米片具有较高的比表面积,不仅可以更为有效地吸附染料分子,还因其量子限域效应大大增强了光生电荷的分离效率和电子转移效率,改善了电子沿平面方向的传输能力以及光生载流子的寿命,从而显著提高g-C₃N₄纳米片的光催化产氢活性。     

硫化镉反蛋白石光子晶体制备及光解水制氢

对硫化镉反蛋白石结构光子晶体薄膜进行了可控合成,用巯基乙酸修饰的纳米晶和P(St-MMA-SPMAP)高分子小球共组装,成功地构筑了反蛋白石结构并用于可见光光解水产氢。结果表明,在可见光(λ≥420 nm)照射下,Cd S-310反蛋白石结构薄膜的光解水产氢性能比硫化镉纳米颗粒提高了一倍。这主要是因为等级孔结构反蛋白石光子晶体特性对催化剂的光催化性能的提升:首先,反蛋白石的周期性结构增加了光子在材料中的传播,提高了催化剂对太阳光的利用率;同时,大孔孔壁是由纳米颗粒堆积而成的,在反应中提供了更多的反应活性位点;此外,孔结构有利于物质的传输和分子的吸附。     

用于光催化分解硫化氢制氢的金属硫化物

硫化氢(H₂S)作为一种剧毒、恶臭的强腐蚀性气体,广泛来源于人类活动和自然界,对动植物生存和环境都具有较大的危害。光催化分解H₂S制氢是一种理想的H₂S处理技术,可以同时实现H₂S的转移和清洁能源氢气的产生。近年来,金属硫化物由于其优异的可见光响应、恰当的能带结构和对H₂S有高的稳定性,因此被广泛地应用于光催化分解H₂S制氢。本文对近年来国内外金属硫化物驱动H₂S资源化利用制氢领域取得的重要进展进行了概述和总结,探讨了不同反应媒介下光催化分解H₂S制氢机制;特别关注了一些为实现高效稳定光催化H₂S资源化利用制氢的优异调控策略;最后,对H₂S资源化利用的挑战和前景进行了展望。     

太阳能光催化制氢研究进展

随着人类社会的快速发展和传统能源的急剧消耗,能源紧缺和环境污染已经成为制约人类社会可持续发展的重要因素,构建清洁的环境友好的可再生新能源体系是当前各国高度关注的焦点和重大战略.在众多绿色环保、可持续新能源选项中,半导体光催化制氢因其可利用清洁可再生的太阳能制取高效清洁氢能,有望完全解决能源紧缺和环境污染问题,成为最有应用前景的技术之一. 本文通过概述半导体光催化制氢原理、半导体光电化学及光电稳定性、半导体光催化制氢效率,重点介绍半导体光催化剂、光生电荷分离及光催化制氢体系等方面若干新进展,并对太阳能光催化制氢技术的发展加以评述和展望.     

太阳能光催化制氢研究进展

由于化石燃料本身的不可持续性,以及燃烧化石燃料释放的大量CO₂ 产生的温室效应、环境污染等严重的全球性问题,构建洁净的、环境友好的、非化石燃料的、可再生新能源体系,已经成为世界各国高度关注的焦点和重大战略。太阳能由于其取之不竭、洁净无污染、可再生等优点,必将在未来的新能源开发中占据举足轻重的地位。而氢能具有高燃烧值、燃烧产物是水因此无环境污染等优点,因此,利用自然界丰富的太阳能光催化制氢作为可持续发展的新能源途径之一,正日益受到国际社会的高度关注。本文简要综述了近年来这一研究领域的一些重要进展,总结了本课题组在半导体光催化制氢研究方面所取得的最新结果,并对太阳能光催化制氢的未来发展进行展望。     

阳离子镍基MOF自组装CdS/PFC-8催化剂用于可见光光催化选择性苯甲醇氧化耦合产氢（英文）

可见光驱动的光催化制氢与有机氧化合成相结合由于其环境友好性和可持续性而极具吸引力,它可以在温和的条件下同时产生清洁的氢气燃料和高价值化学品,而无需牺牲剂。半导体材料和金属有机骨架(MOFs)材料由于其性能和优势,在光催化领域得到了广泛的应用。在这项工作中,我们通过静电自组装成功合成了一种名为Cd S/PFC-8的新型有效催化剂。其中,PFC-8作为镍基金属有机骨架,Cd S/PFC-8复合材料作为无贵金属催化剂,在可见光下具有优异的光催化制氢和苯甲醇氧化性能。对Cd S/PFC-8复合材料进行了一系列催化表征。X射线衍射(XRD)和扫描电子显微镜(SEM)结果表明了Cd S/PFC-8复合材料的成功合成。X射线光电子能谱(XPS)表明了Cd S纳米棒与PFC-8之间存在一定的界面相互作用。通过紫外-可见漫反射光谱(DRS)、光致发光光谱(PL)和电化学测试对光电性能进行了表征,表明Cd S/PFC-8复合材料的可见光响应和光催化可行性。对不同催化剂的光催化实验结果进行比较,在可见光下,Cd S/PFC-8复合材料将H2的产生与苯甲醇的选择性氧化耦合,表现出显著的H2产率3376μmol...     

多壁碳纳米管修饰的CdS/TiO2复合光催化材料的制备及其光解水制氢特性

以P25 TiO₂(德国Degussa化学公司)粉末为原料采用溶胶-凝胶法制备了含有不同CdS质量分数的复合光催化剂,利用多壁碳纳米管(MWCNTs)对CdS/TiO₂进行修饰,制备了一系列不同CdS含量的MWCNTs/CdS/TiO₂光催化材料。对所得的光催化剂进行了扫描电镜、低温氮吸附-脱附及光解水制氢活性的表征。研究了MWCNTs对CdS/TiO₂催化剂体系光解水制氢活性的影响。结果表明,MWCNTs的引入均使得光解水产氢量(14.0 μmol)增加,与未加入MWCNTs的复合光化剂产氢量(11.6 μmol)相比,平均产氢率增加了18%,最高可达21%。     

Construction of Shallow Surface States through Light Ni Doping for High‐Efficiency Photocatalytic Hydrogen Production of CdS Nanocrystals

Ni‐doped CdS nanowires were synthesized by a simple one‐step method. X‐ray diffraction, X‐ray photoelectron spectroscopy, and photoluminescence spectroscopy confirmed that light Ni doping can form shallow surface states due to the presence of substitutional Ni ions, and heavy Ni doping can form deep surface states due to the presence of interstitial Ni ions. Surface photovoltage spectroscopy and transient photovoltage measurements revealed that the shallow surface states can prolong the lifetime of the photogenerated charge carriers, whereas the deep surface states lead to recombination of the photogenerated charge carriers. The relationship between different surface states and the photocatalytic performance of CdS nanocrystals are discussed. The enhanced density of shallow surface states due to light Ni doping significantly promotes photocatalytic H₂ production.     

Production of Hydrogen Peroxide by Photocatalytic Processes

Hydrogen peroxide (H₂O₂) has received increasing attention because it is not only a mild and environmentally friendly oxidant for organic synthesis and environmental remediation but also a promising new liquid fuel. The production of H₂O₂ by photocatalysis is a sustainable process, since it uses water and oxygen as the source materials and solar light as the energy. Encouraging processes have been developed in the last decade for the photocatalytic production of H₂O₂. In this Review we summarize research progress in the development of processes for the photocatalytic production of H₂O₂. After a brief introduction emphasizing the superiorities of the photocatalytic generation of H₂O₂, the basic principles of establishing an efficient photocatalytic system for generating H₂O₂ are discussed, highlighting the advanced photocatalysts used. This Review is concluded by a brief summary and outlook for future advances in this emerging research field.