From Extended Nanofluidics to an Autonomous Solar‐Light‐Driven Micro Fuel‐Cell Device

Autonomous micro/nano mechanical, chemical, and biomedical sensors require persistent power sources scaled to their size. Realization of autonomous micro‐power sources is a challenging task, as it requires combination of wireless energy supply, conversion, storage, and delivery to the sensor. Herein, we realized a solar‐light‐driven power source that consists of a micro fuel cell (μFC) and a photocatalytic micro fuel generator (μFG) integrated on a single microfluidic chip. The μFG produces hydrogen by photocatalytic water splitting under solar light. The hydrogen fuel is then consumed by the μFC to generate electricity. Importantly, the by‐product water returns back to the photocatalytic μFG via recirculation loop without losses. Both devices rely on novel phenomena in extended‐nano‐fluidic channels that ensure ultra‐fast proton transport. As a proof of concept, we demonstrate that μFG/μFC source achieves remarkable energy density of ca. 17.2 mWh cm⁻² at room temperature.     

光催化完全分解水制氢研究进展

由完全分解水的特殊性出发,从材料的结构和能带设计以及材料的表面修饰等方面对完全分解水光催化剂的研制及其分解水产氢产氧性能进行了评述.介绍了Z型体系在完全分解水制氢方面的原理,以及目前已经开发出来的几个Z型体系.对光催化完全分解水研究中存在的问题进行了简单分析.     

硫化锌镉固溶体光催化分解水产氢研究现状

硫化锌镉（Cd_1-xZn_xS,0 < x < 1）固溶体因其优异的活性、可调谐的能带结构在光催化分解水制氢领域备受关注,但其较快的光生电荷复合速率和光腐蚀仍阻碍了其进一步应用。因此,研究者们针对其固有缺陷进行了大量改性工作。我们首先简述了光催化反应热力学与动力学特征,随后详细综述了近年来Cd_1-xZn_xS在光解水制氢领域的研究进展,包括其结构调控、异质结构建、杂原子掺杂等方面,简要分析了Cd_1-xZn_xS光催化分解水所面临的挑战和问题,并对近期研究进行了展望。     

还原氧化石墨烯/介孔TiO2复合材料的合成及其光解水制氢性能

采用溶胶凝胶法,以钛酸四异丙酯(TTIP)为钛源,十六烷基三甲基溴化铵(CTAB)为模板剂合成了介孔二氧化钛样品mTiO_2,考察了合成温度、水量、模板剂用量和焙烧温度对其在紫外光条件下光催化产氢活性的影响。结果显示,在350℃下焙烧后,样品由无定形结构转变为锐钛矿相;随着焙烧温度的提高,锐钛矿相结构产物的结晶度提高,当焙烧温度超过550℃后,样品大部分转变为金红石相。以合成温度为30℃,模板剂用量(nCTAB/nTiO_2)为0.2,水量(nH2O/nTiO_2)为100,焙烧温度为450℃条件下合成的m-TiO_2样品为催化剂,当催化剂用量为0.4 g·L-1,体系中甲醇浓度高于20%(V/V)时,其紫外光条件下的光催化产氢活性达170 mmol·g-1·h-1。采用水热法将氧化石墨烯(GO)与m-TiO_2复合制备了一系列还原氧化石墨烯/介孔TiO_2复合材料(rGO/m-TiO_2),其晶相结构为锐钛矿相。当r GO复合量(wGO/wTiO_2)为0.01时,样品在紫外光下的产氢活性为241 mmol·g-1·h-1,能量转化效率达7.4%,较未复合样品提高了42.3%;在可见光条件下,其产氢活性达9 mmol·g-1·h-1。     

A Heterogeneous Photocatalytic Hydrogen Evolution Dyad: [(tpy

The development of an artificial heterogeneous dyad by covalently anchoring a hydrogen‐evolving molecule catalyst to a semiconductor photosensitizer through a bridging ligand is highly challenging. Herein, we adopt the inorganic–organic hybrid CdS–DETA NSs (DETA=diethylenetriamine, NSs=nanosheets) as initial matrix to successfully construct an imine bond (‐CH=N‐) linked heterogeneous dyad [CdS?N=CH?Ni] through the condensation reaction between the amino groups of CdS–DETA and the aldehyde group of the water reduction molecular catalyst, [(tpy‐CHO)₂Ni]Cl₂ (tpy=terpyridine). The [CdS?N=CH?Ni] enables a turnover number (TON) of about 43 815 versus Ni catalysts and an initial turnover frequency (TOF) of approximately 0.47 s^?1 in 26 h under visible‐light irradiation (λ>420 nm). The apparent quantum yield (AQY) reaches (9.9±0.8) % at 420 nm. Under optical conditions, the [CdS?N=CH?Ni] can achieve a considerable amount of hydrogen production, 507.1±27 μmol H₂ for 6 h, which is 1.27 times that generated from the mechanically mixed system of CdS–DETA NSs and [(tpy‐CH=NR)₂Ni]Cl₂ ( III ) under otherwise identical conditions. Furthermore, its TON value based on Ni species is also higher than that of the mixed system of CdS–DETA and III .     

光催化“全”分解水制H_2与牺牲体系产H_2的关系

多相光催化"全"分解水制H_2的研究已走过约40年路程,至今未获得真正的突破,目前国内、外发表的许多可见光催化牺牲体系放H_2的文章,虽然它在氢离子还原机理方面有一定的参考意义,但它不能解决光催化"全"分解水制H_2问题,本文提醒我国光催化界:勿把可见光牺牲体系产H_2研究的结果,当成我们在分解水制H,方面取得的进展,应认真总结过去失败的经验教训,兼顾热力学和动力学两方面的要求,制订出正确的"全"分解水制H_2催化剂的研究策略。     

Surfactant–Thermal Method to Synthesize a Novel Two‐Dimensional Oxochalcogenide

A new two‐dimensional (2D) oxosulfide, (N₂H₄)₂Mn₃Sb₄S₈(μ₃‐OH)₂ ( 1 ), has been successfully synthesized under surfactant–thermal conditions with hexadecyltributylphosphonium bromide as the surfactant. Compound 1 has a layered structure and contains a novel [Mn₃(μ₃‐OH)₂]_n chain along the b‐axis. The photocatalytic activity for compound 1 has been demonstrated under visible‐light irradiation and continuous H₂ evolution was observed. Our results indicate that surfactant–thermal synthesis could be a promising method for growing novel crystalline oxochalcogenides with interesting structures and properties.     

二硫化钼析氢电催化剂

电解水与一次可再生能源耦合,可同时提供洁净制氢方式与先进的能源转化技术,有望在未来清洁能源经济中扮演重要角色,而实现这一美好愿景的关键在于研发高活性、低成本的析氢/析氧电催化材料。二硫化钼(MoS₂)是颇具代表性的非贵金属析氢电催化材料,纵观其研究历程,先导性理论预测与材料设计、先进制备与表征技术的应用均在改性研究中发挥了至关重要的作用,这也从一个侧面折射出当代电催化剂的研究模式与发展趋势。本文按照重要发现与进展的时间顺序,梳理了MoS₂析氢电催化剂的发展历程,重点论述了增多边缘活性位、提高导电性、构筑基面活性位等改性策略的实施方法、效果与机理,最后从全领域总结了MoS₂析氢电催化剂的研究启示并展望其未来发展趋势。     

气-固相光催化分解硫化氢制氢

利用气-固相反应初步考察了几种常用半导体光催化剂在无氧条件下分解硫化氢产氢的活性.在研究的TiO2,CdS,ZnS,ZnO和ZnIn2S4等催化剂中,ZnS具有较高的光催化产氢活性.在ZnS上担载贵金属Ir可明显提高产氢速率,在ZnS制     

Conjugated Polymers: Catalysts for Photocatalytic Hydrogen Evolution

Conjugated polymers, comprising fully π‐conjugated systems, present a new generation of heterogeneous photocatalysts for solar‐energy utilization. They have three key features, namely robustness, nontoxicity, and visible‐light activity, for photocatalytic processes, thus making them appealing candidates for scale‐up. Presented in this Minireview, is a brief summary on the recent development of various promising polymer photocatalysts for hydrogen evolution from aqueous solutions, including linear polymers, planarized polymers, triazine/heptazine polymers, and other related organic conjugated semiconductors, with a particular focus on the rational manipulation in the composition, architectures, and optical and electronic properties that are relevant to photophysical and photochemical properties. Some future trends and prospects for organic conjugated photocatalysts in artificial photosynthesis, by water splitting, are also envisaged.     

A Cocatalyst that Stabilizes a Hydride Intermediate during Photocatalytic Hydrogen Evolution over a Rhodium‐Doped TiO2 Nanosheet

The hydrogen evolution reaction using semiconductor photocatalysts has been significantly improved by cocatalyst loading. However, there are still many speculations regarding the actual role of the cocatalyst. Now a photocatalytic hydrogen evolution reaction pathway is reported on a cocatalyst site using TiO₂ nanosheets doped with Rh at Ti sites as one‐atom cocatalysts. A hydride species adsorbed on the one‐atom Rh dopant cocatalyst site was confirmed experimentally as the intermediate state for hydrogen evolution, which was consistent with the results of density functional theory (DFT) calculations. In this system, the role of the cocatalyst in photocatalytic hydrogen evolution is related to the withdrawal of photo‐excited electrons and stabilization of the hydride intermediate species; the presence of oxygen vacancies induced by Rh facilitate the withdrawal of electrons and stabilization of the hydride.     

Photocatalytic hydrogen generation from water with iron carbonyl phosphine complexes: improved water reduction catalysts and mechanistic insights

An extended study of a novel visible-light-driven water reduction system containing an iridium photosensitizer, an in situ iron(0) phosphine water reduction catalyst (WRC), and triethylamine as sacrificial reductant is described. The influences of solvent composition, ligand, ligand-to-metal ratio, and pH were studied. The use of monodentate phosphine ligands led to improved activity of the WRC. By applying a WRC generated in situ from Fe(3) (CO)(12) and tris[3,5-bis(trifluoromethyl)phenyl]phosphine (P[C(6)H(3)(CF(3))(2)](3), Fe(3)(CO)(12)/PR(3)=1:1.5), a catalyst turnover number of more than 1500 was obtained, which constitutes the highest activity reported for any Fe WRC. The maximum incident photon to hydrogen efficiency obtained was 13.4% (440 nm). It is demonstrated that the evolved H(2) flow (0.23 mmol H(2) h(-1) mg(-1) Fe(3)(CO)(12)) is sufficient to be used in polymer electrolyte membrane fuel cells, which generate electricity directly from water with visible light. Mechanistic studies by NMR spectroscopy, in situ IR spectroscopy, and DFT calculations allow for an improved understanding of the mechanism. With respect to the Fe WRC, the complex [HNEt(3)](+)[HFe(3)(CO)(11)](-) was identified as the key intermediate during the catalytic cycle, which led to light-driven hydrogen generation from water.     

Development of Strong Visible-Light-Absorbing Cyclometalated Iridium(III) Complexes for Robust and Efficient Light-Driven Hydrogen Production

Weak light absorption of common Ir(III) complexes (e. g., using phenylpyridine as the ligand) has hindered their applications in photocatalytic hydrogen generation from water as an efficient photosensitizer. To address this issue, a series of cyclometalated Ir(III) complexes (Ir1–Ir5), featuring different electron-donating substituents to enhance the absorptivity, have been synthesized and studied as photosensitizers (PSs) for light-driven hydrogen production from water. Ir6–Ir7 were prepared as fundamental systems for comparisons. Electron donors, including 9-phenylcarbazole, triphenylamine, 4,4′-dimethoxytriphenylamine, 4,4′-di(N-hexylcarbazole)triphenylamine moieties were introduced on 6-(thiophen-2-yl)phenanthridine-based cyclometalating (C^N) ligands to explore the donor effect on the hydrogen evolution performance of these cationic Ir(III) complexes. Remarkably, Ir4 with 4,4′-dimethoxytriphenylamine achieved the highest turn-over number (TON) of 12 300 and initial turnover frequency (TOF_i) of 394 h⁻¹, with initial activity (activity_i) of 547 000 μmol g⁻¹ h⁻¹ and initial apparent quantum yield (AQY_i) of 9.59 %, under the illumination of blue light-emitting diodes (LEDs) for 105 hours, which demonstrated a stable three-component photocatalytic system with high efficiency. The TON (based on n(H₂)/n(PSr)) in this study is the highest value reported to date among the similar photocatalytic systems using Ir(III) complexes with Pt nanoparticles as catalyst. The great potential of using triphenylamine-based Ir(III) PSs in boosting photocatalytic performance has also been shown.     

Inorganic Photocatalysts for Overall Water Splitting

Photocatalytic water splitting using semiconductor photocatalysts has been considered as a “green” process for converting solar energy into hydrogen. The pioneering work on electrochemical photolysis of water at TiO₂ electrode, reported by Fujishima and Honda in 1972, ushered in the area of solar fuel. As the real ultimate solution for solar fuel‐generation, overall water splitting has attracted interest from researchers for some time, and a variety of inorganic photocatalysts have been developed to meet the challenge of this dream reaction. To date, high‐efficiency hydrogen production from pure water without the assistance of sacrificial reagents remains an open challenge. In this Focus Review, we aim to provide a whole picture of overall water splitting and give an outlook for future research.