GaN:ZnO solid solution as a photocatalyst for visible-light-driven overall water splitting

Photocatalytic overall water splitting has been studied extensively from the viewpoint of solar energy conversion. Despite numerous attempts, none have yielded satisfactory results for the development of photocatalysts, which work under visible light irradiation to efficiently utilize solar energy. We report here the first example of visible-light-driven overall water splitting on a novel oxynitride photocatalyst, a solid solution of GaN and ZnO with a band gap of 2.58-2.76 eV, modified with RuO2 nanoparticles. In contrast to the conventional non-oxide photocatalysts, such as CdS, the solid solution is stable during the overall water splitting reaction. This is the first example of achieving overall water splitting by a photocatalyst with a band gap in the visible light region, which opens the possibility of new non-oxide-type photocatalysts for energy conversion.     

Photocatalytic mechanisms of modified titania under visible light

Heterogeneous photocatalysis with titania under visible light has increasingly been a focus for research. Metal or non-metal doping, surface sensitization, semiconductor coupling, precious metal deposition and increasing crystal defects have been used to enhance the photocatalytic activity of titania under visible light. Based on the research results of different modification methods in recent years, some mechanisms from the excitation, bulk diffusion and surface transfer of photoinduced charge carriers, such as band gap modification, changing the excitation path, promoting the separation of photogenerated charge carrier, improving the surface adsorption and reaction, and synergistic effects, for photocatalysis under visible light are discussed and the development trend in this field is predicted.     

Photocatalytic activity of titanium dioxide modified with thiourea under the action of visible light

Photocatalyst powders were synthesized from nanosized titanium dioxide crystals modified by sintering with thiourea (TU). The powders contained anatase crystals of various sizes. TU-TiO₂ powders absorbed visible light to produce an oxidizer (oxidizing iodide) and a reducing agent (reducing tetranitromethane). The activity of TU-TiO₂ correlated with the size of nanocrystals. The photocatalytic activity of TU-TiO₂ was suggested to be related to impurity states appearing during modification in the forbidden band of TiO₂.     

Photocatalytic activity of silicon nanowires under UV and visible light irradiation

The communication reports on the high performance of hydrogen-terminated silicon nanowires and silicon nanowires coated with metal (Ag, Cu) nanostructures for the photodegradation of rhodamine B under UV and visible light irradiation.     

Photocatalytic hydrogen evolution from water on SiC under visible light irradiation

A kind of green SiC fine powder was characterized by XRD and UV-Vis diffuse reflectance, and studied in the photocatalytic splitting of water. The results showed that the green SiC fine powder can absorb visible light and split water with the formation of hydrogen under visible light irradiation. The activity is affected significantly by the initial pH of solutions and the types of cheap reagents, where the addition of OH⁻ or S²⁻ leads to a remarkable increase in the activity.     

Photocatalytic activity of Fe and Cu co-doped TiO2 nanoparticles under visible light

Journal of Sol-Gel Science and Technology - The photocatalytic activity of single transition metal-doped TiO2 nanoparticles is well established. This article reports the synthesis of Fe and Cu...     

Photocatalytic water oxidation with nonsensitized IrO2 nanocrystals under visible and UV light

Rutile IrO(2) is known as being among the best electrocatalysts for water oxidation. Here we report on the unexpected photocatalytic water oxidation activity of 1.98 nm ± 0.11 nm succinic acid-stabilized IrO(2) nanocrystals. From aqueous persulfate and silver nitrate solution the nonsensitized particles evolve oxygen with initial rates up to 0.96 μmol min(-1), and with a quantum efficiency of at least 0.19% (measured at 530 nm). The catalytic process is driven by visible excitations from the Ir-d(t(2g)) to the Ir-d(e(g)) band (1.5-2.75 eV) and by ultraviolet excitations from the O-p band to the Ir-d(e(g)) (>3.0 eV) band. The formation of the photogenerated charge carriers can be directly observed with surface photovoltage spectroscopy. The results shed new light on the role of IrO(2) in dye- and semiconductor-sensitized water splitting systems.     

Highly stable water splitting on oxynitride TaON photoanode system under visible light irradiation

Highly stable photoelectrochemical water splitting is demonstrated for the first time on a tantalum oxynitride (TaON) photoanode under visible light irradiation. Highly dispersed CoO(x) nanoparticles on the TaON photoanode efficiently scavenge photogenerated holes and effectively suppress self-oxidative deactivation of the TaON surface, resulting in a stable photocurrent. The use of highly dispersed CoO(x) cocatalyst on TaON together with phosphate solutions significantly increased the photocurrent due to the formation of a cobalt/phosphate phase. This enabled us to stably split water into H(2) and O(2) under visible light irradiation at a relatively low applied bias (0.6 V vs Pt counter electrode).     

磷化镍修饰磷掺杂氧化镓可见光催化水分解产氢

以Ga₂O₃半导体为前驱体,用浸渍加低温磷化法制备了P掺杂Ga₂O₃表面修饰Ni₂P光催化剂(x-Ni₂P/Ga₂O₃-P_y,x代表Ni²⁺和Ga₂O₃的物质的量之比,y代表NaH₂PO·H₂O与Ga₂O₃的物质的量之比)。5%-Ni₂P/Ga₂O₃-P₆催化剂展现出在纯水中光催化析氢的高活性,在430 nm光照下的光量子效率为0.22%。机理研究结果表明Ni₂P修饰和P掺杂扩展了催化剂的光响应范围,同时提升了载流子分离迁移效率,其长周期光催化反应稳定性明显优于未磷化催化剂。     

Photocatalytic overall water splitting under visible light by TaON and WO3 with an IO3-/I- shuttle redox mediator

Photocatalytic water splitting into H2 and O2 under visible-light irradiation (lambda > 420 nm) is demonstrated using the oxynitride Pt-TaON for H2 evolution and a Pt-WO3 catalyst for O2 evolution in an IO3-/I- shuttle redox-mediated system.     

Photocatalytic activity of SrTiO3 codoped with nitrogen and lanthanum under visible light illumination

Yellow SrTiO3 powders codoped with nitrogen and lanthanum (STO:N,La) were studied as visible light photocatalysts. The crystal phase of STO:N,La exhibited a pure perovskite phase, and O and Sr sites atoms were substitutionally doped with N and La atoms, respectively. The first principle calculation of STO:N,La indicated that the edge of the N(2p) band is situated above the valence band, which consisted of O(2p) orbitals, and the La orbitals did not exist in the band gap of SrTiO3. STO:N,La exhibited a higher oxidation activity of gaseous 2-propanol under vis illumination than SrTiO3 doped only with nitrogen (STO:N). The high activity of STO:N,La was due to the decrease in the oxygen vacancies, which acted as electron-hole recombination centers, because codoping with La3+ and N3- ions maintained the charge balance. The optimum doping density of N and La for visible light activity was 0.5%, and STO:N,La(0.5%) had an activity under UV illumination similar to pure SrTiO3.     

磷化镍修饰磷掺杂氧化镓可见光催化水分解产氢

以Ga₂O₃半导体为前驱体,用浸渍加低温磷化法制备了P掺杂Ga₂O₃表面修饰Ni₂P光催化剂(x-Ni₂P/Ga₂O₃-P_y,x代表Ni²⁺和Ga₂O₃的物质的量之比,y代表NaH₂PO·H₂O与Ga₂O₃的物质的量)。5%-Ni₂P/Ga₂O₃-P₆催化剂展现出在纯水中光催化析氢的高活性,在430 nm光照下的光量子效率为0.22%。机理研究结果表明Ni₂P修饰和P掺杂扩展了催化剂的光响应范围,同时提升了载流子分离迁移效率,其长周期光催化反应稳定性明显优于未磷化催化剂。     

Photocatalytic CdSe QDs-decorated ZnO nanotubes: an effective photoelectrode for splitting water

Arrays of ZnO nanorods (NRs) were successfully converted into nanotubes (NTs), used as photoelectrodes in photoelectrochemical (PEC) cells after their sensitization with CdSe quantum dots (QDs) and a strong correlation between the PEC performance and geometrical structure of ZnO NTs@CdSe(QDs) and ZnO NRs@CdSe(QDs) was established under the same conditions.     

CdS的结构参数对其可见光分解水产氢性能的影响

采用水热/溶剂热法合成了球形、棒状和叶子状的CdS,并采用扫描电子显微镜(SEM)、X射线粉末衍射仪(XRD)、紫外-可见漫反射光谱(UV-vis DRS)、荧光光谱(PL)、比表面积及孔隙率分析仪(BET)等技术对其结构和光吸收特性进行了表征.考察了4种CdS光催化剂的可见光分解水产氢性能,并考察了CdS的结构参数对其活性的影响.结果表明,当Pt的负载量为1.2%(质量分数)时,L-CdS产氢速率最高,为47.77 mmol·h~(-1)·g~(-1).结构表征显示,L-CdS(002)晶面衍射峰强度特别强.(002)晶面是高指数晶面,比表面能大,这可能是其活性高的主要原因.紫外-可见漫反射光谱和荧光光谱结果也表明,L-CdS具有很好的可见光响应和较弱的荧光强度.     

Photocatalytic oxidation of 4-chlorophenol using thermosensitive zinc phthalocyanine copolymer under visible light irradiation

A novel thermosensitive photocatalyst,P(NIPA-co-ZnMPc),has been prepared using zinc tetra(N-carbonylacrylic)aminophthalocya-nine(ZnMPc) to copolymerize with N-isopropylacrylamide(NIPA).The lower critical solution temperature(LCST) of P(NIPA-co-ZnMPc) measured by differential scanning calorimetry(DSC) was 33.5 °C.P(NIPA-co-ZnMPc) effectively catalyzes the oxidation of 4-chlorophenols(4-CP) using oxygen as oxidant under the visible light irradiation,and it has higher photocatalytic activity than ZnMPc under t...     

Photocatalytic water splitting using semiconductor particles: History and recent developments

Overall water splitting to produce H₂ and O₂ over a semiconductor photocatalyst using solar energy is a promising process for the large-scale production of clean, recyclable H₂. Numerous attempts have been made to develop photocatalysts that function under visible-light irradiation to efficiently utilize solar energy. In general, overall water splitting over a photocatalyst particle can be achieved by modifying the photocatalyst with a suitable cocatalyst to provide an active redox site. Therefore, the development of active photocatalytic materials has relied on both photocatalysts and cocatalysts. This review article describes the historical development of water-splitting photocatalysts.     

可见光照射下温敏锌酞菁共聚物光催化氧化对氯苯酚

将含有不饱和双键的四马来酰胺基锌酞菁（ZnMPc）与N-异丙基丙烯酰胺（NIPA）共聚,制备得到一种新型温敏锌酞菁共聚物光催化剂：P（NIPA—co—ZnMPc）,采用差示扫描量热法测得其低临界溶解温度（LCST）为33．5℃．在可见光照射下利用氧气作为氧化剂,P（NIPA—co-ZnMPc）~g有效地催化氧化对氯苯酚（4-CP）,与小分子ZnMPc相比,P（NIPA-co-ZnMPc）具有更高的光催化活性．两者在水溶液中的紫外．可见光谱图显示,共聚后大分子链的阻隔作用能有效地抑制酞菁分子的二聚,从而大大提高了其催化活性．温度对其光催化活性的实验结果显示,P（NIPA-co-ZnMPc）在其LCST附近具有最高的催化效率,说明催化剂的聚集态结构对其光催化活性产生直接影响,通过测定其在不同温度下的流体力学半径,可推测在其LCST附近发生了分子间的疏水聚集,会对4-CP起富集作用,从而加快了光催化反应速率．该光催化剂可通过均相催化异相分离实现循环利用,实验表明该催化剂具有较高的稳定性．     

Photocatalytic activities of various pentavalent bismuthates under visible light irradiation

LiBiO₃, NaBiO₃, MgBi₂O₆, KBiO₃, ZnBi₂O₆, SrBi₂O₆, AgBiO₃, BaBi₂O₆ and PbBi₂O₆ were synthesized by various processes such as hydrothermal treatment, heating and so on. These materials were examined for their photocatalytic activities in the decolorization of methylene blue and decomposition of phenol under visible light irradiation. For methylene blue decolorization, the presence of KBiO₃ resulted in complete decoloration within 5 min. For phenol decomposition, NaBiO₃ showed the highest activity, while LiBiO₃, SrBi₂O₆ and BaBi₂O₆ possessed almost comparable decomposition rates. Their decomposition rates were apparently higher than that by anatase (P25) under UV irradiation.     

Enhanced photocatalytic activity of SiC modified by BiVO4 under visible light irradiation

SiC-BiVO₄-P and SiC-BiVO₄-H composites have been prepared by precipitation method and hydrothermal method, respectively. Rod-like BiVO₄ particles dispersed on the surface of micro-sized SiC particles homogeneously in SiC-BiVO₄-H. Due to the formed heterostructure between BiVO₄ and SiC, photo-generated electrons and holes were effectively separated. Under visible light irradiation, SiC-BiVO₄-H exhibited the best performance for photocatalytic oxidation of Rhodamine B, achieved about 7.5 times improvement in photocatalytic degradation rate constants compared with that of the pristine SiC powder. The possible photocatalysis mechanism of SiC/BiVO₄ related to the band positions of the semiconductors under visible light irradiation was also discussed in detail. In addition, the radicals trapping experiments revealed that all three radicals (holes, OH, and O₂^?) play an important role in the Rhodamine B degradation.     

吸附法制备CdS/HKLBT复合催化材料及其可见光制氢活性

采用吸附法制备了CdS和层状物的复合光催化材料CdS/HKLBT(吸附),并采用X射线衍射(XRD)、紫外-可见漫反射(DRS)、透射电子显微镜(TEM)等技术对其进行了表征和分析。实验对比了吸附法制备的复合材料与离子交换法制备材料活性差异,考察了CdS负载量对复合物制氢活性的影响.结果表明,表面复合也能明显提高CdS的可见光制氢活性,当CdS复合量为15%(质量分数)时活性最高,达到532μmol/h,与离子交换法制备的光催化剂的产氢速率接近;而过多CdS的负载造成载流子迁移的障碍,从而不利于活性的提高.