TiO 2表面的光催化分解水反应是氢能技术中具有重要意义的基础问题之一，并得到了广泛的研究。然而，存在的第一个反应步骤，直接光解水，已被忽视。在这里，我们提供了明确的实验证据表明，吸附在金红石型TiO 2（110）-1 \times 1表面的水分子可以解离紫外线照射下，使用低温扫描隧道显微镜。结果表明，在光催化作用下，Ti（Ti_（5c））五配位上的一个水分子发生解离，在Ti_（5c）上生成一个羟基，在桥氧排上生成另一个羟基。我们的研究结果揭示了光催化水裂解反应链中缺失的一环，这大大有助于详细了解潜在的机制。
英文摘要：
Photocatalytic water splitting reaction on TiO2 surface is one of the fundamental issues that bears significant implication in hydrogen energy technology and has been extensively studied. However, the existence of the very first reaction step, the direct photo-dissociation of water, has been disregarded. Here, we provide unambiguously experimental evidence to demonstrate that adsorbed water molecules on reduced rutile TiO2(110)-1\times1 surface can be dissociated under UV irradiation using low temperature scanning tunneling microscopy. It is identified that a water molecule at fivefold coordinated Ti (Ti5c) site can be photocatalytically dissociated, resulting in a hydroxyl at Ti5c and another hydroxyl at bridge oxygen row. Our findings reveal a missing link in the photocatalytic water splitting reaction chain, which greatly contribute to the detailed understanding of underlying mechanism.
Photocatalytic water splitting has greatly stimulated as an ideal technique for producing hydrogen (H$_{2}$) fuel by employing two renewable sources, i.e., water and solar energy. Here, we have adopted a facile hydrothermal approach for the successful synthesis of reduced graphene oxide (rGO) incorporated Fe/MgO nanocomposites followed by thermal treatment at inert atmosphere to investigate their ability for photodegradation and photocatalytic hydrogen evolution via water splitting. Transmission Electron Microscopy images of Fe/MgO-rGO nanocomposite ensured the distribution of Fe/MgO nanoparti…
Time-resolved X-ray absorption spectroscopy has been utilized to monitor the bimolecular electron transfer in a photocatalytic water splitting system for the first time. This has been possible by uniting the local probe and element specific character of X-ray transitions with insights from high-level ab initio calculations. The specific target has been a heteroleptic [Ir$^{\rm III}$(ppy)$_2$(bpy)]$^+$ photosensitizer, in combination with triethylamine as a sacrificial reductant and Fe$_3$(CO)$_{12}$ as a water reduction catalyst. The relevant molecular transitions have been characterized via h…
A sustainable photocatalytic pathway for concurrent hydrogen and value-added chemical production utilizing microalgae as bio-scavenger in water
WPI, International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University（九州大学碳中和能源研究国际高等研究院（WPI-I2CNER））；Department of Automotive Science, Graduate School of Integrated Frontier Sciences, Kyushu University（九州大学前沿融合科学研究生院汽车科学系）；Laboratório de Biotecnologia BraPhyto, Faculdade de Ciências Aplicadas (FCA), Universidade Estadual de Campinas (UNICAMP)（坎皮纳斯州立大学（UNICAMP）应用科学学院BraPhyto生物技术实验室）；Mitsui Chemicals, Inc. - Carbon Neutral Research Center (MCI-CNRC), Kyushu University（三井化学株式会社-碳中和研究中心（MCI-CNRC））
Due to the energy supply pressure caused by non-renewable fuels as well as the environment-related issues, the efficient conversion of solar-chemical energy via photo-induced water splitting is one of the promising strategies to address the existing problems. To strengthen the overall catalytic performance of photocatalytic hydrogen (H2) and oxygen (O2) evolution, the selection and construction of cocatalysts are crucial. Recently, the semiconductor photocatalysts have been well modified with the loaded cocatalysts as the active sites by extending the light harvest, promoting the electron sepa…
SrTiO$_3$ is a highly efficient photocatalyst for the overall water splitting reaction under UV irradiation. However, an atomic-level understanding of the active surface sites responsible for the oxidation and reduction reactions is still lacking. Here we present a unified experimental and computational account of the photocatalytic activity at the SrO- and TiO$_2$- terminations of aqueous-solvated [001] SrTiO$_3$. Our experimental findings show that the overall water-splitting reaction proceeds on the SrTiO$_3$ surface only when the two terminations are simultaneously exposed to water. Our si…
Water structure near the surface of Weyl semimetals as catalysts in photocatalytic proton reduction
Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry, Paderborn University（帕德博恩大学凝聚态动力学与可持续系统设计中心理论化学教席）
Recently, hydrogen generation by water-splitting photocatalysts is attracting attention as a sustainable and clean energy resource. Photocatalytic hydrogen-generation systems are much simpler, cheaper, and easier to scale up than the coupled systems of electrolysis and solar cells, wind-power generation, etc. However, photocatalytic hydrogen generation is currently inefficient. This paper proposes the monolayer of boron phosphide as a stable highly-efficient water-splitting photocatalyst by high-precision density-functional theory calculations using a HSE06 functional with a solvent effect. Th…
Water absorption and dissociation processes on pristine low-index TiO$_2$ interfaces are important but poorly understood outside the well-studied anatase (101) and rutile (110). To understand these, we construct three sets of machine learning potentials that are simultaneously applicable to various TiO$_2$ surfaces, based on three density-functional-theory approximations. We compute the water dissociation free energies on seven pristine TiO$_2$ surfaces, and predict that anatase (100), anatase (110), rutile (001), and rutile (011) surfaces favor water dissociation, anatase (101) and rutile (10…
We study ion pair dissociation in water at ambient conditions using a combination of classical and ab initio approaches. The goal of this study is to disentangle the sources of discrepancy observed in computed potentials of mean force. In particular we aim to understand why some models favor the stability of solvent-separated ion pairs versus contact ion pairs. We found that some observed differences can be explained by non-converged simulation parameters. However, we also unveil that for some models, small changes in the solution density can have significant effects on modifying the equilibri…
Strong electric fields can accelerate molecular dissociation reactions. The phenomenon known as the Wien effect was previously observed using high-voltage electrolysis cells that produced fields of about 10^7 V m-1, sufficient to accelerate the dissociation of weakly bound molecules (e.g., organics and weak electrolytes). The observation of the Wien effect for the common case of water dissociation (H2O = H+ + OH-) has remained elusive. Here we study the dissociation of interfacial water adjacent to proton-permeable graphene electrodes and observe strong acceleration of the reaction in fields r…
Recent experiments demonstrated that interfacial water dissociation (H2O = H+ + OH-) could be accelerated exponentially by an electric field applied to graphene electrodes, a phenomenon related to the Wien effect. Here we report an order-of-magnitude acceleration of the interfacial water dissociation reaction under visible-light illumination. This process is accompanied by spatial separation of protons and hydroxide ions across one-atom-thick graphene and enhanced by strong interfacial electric fields. The found photo-effect is attributed to the combination of graphene's perfect selectivity wi…
Photocatalytic- and Photoelectrochemical water splitting is currently performed using radiation sources with wavelengths < 1000 nm, i.e. in the near infrared range (NIR). The fact that water has a broad absorption band, which lies at wavenumbers between 3000 and 3700 cm-1 (stretching mode) and 1650 cm-1 (bending mode), has not been taken into account so far. We irradiated the steel anode with a mid-infrared LED (lambda=3300 nm) while water electrolysis was performed in pH 7-corrected phosphate buffer solution. A significant shift (270 mV) of the cyclic voltammetry (CV) curve towards lower pote…
Interactions between molecules and electrode surfaces play a key role in electrochemical processes and are a subject of extensive research, both experimental and theoretical. In this manuscript, we address the water dissociation reaction on a Pd(111) electrode surface, modelled as a slab embedded in an external electric field. We aim at unraveling the relationship between surface charge and zero-point-energy in aiding or hindering this reaction. We calculate energy barriers with dispersion-corrected density-functional theory and an efficient parallel implementation of the nudged-elastic-band m…
Reactor based XPS and other in-situ studies on the Effect of Substitution of Bismuth for Indium in Defect Laden Indium Oxide Hydroxide BizIn2-zO3-x(OH)y on the Photocatalytic Hydrogenation of Carbon Dioxide
Bi（III）取代Bi In 2-zO 3-xOHy晶格中的In（III），可显著提高Bi In 2-zO 3-x（OH）y对逆水煤气变换（RWGS）反应CO2 + H2 -> CO + H2 O的光催化活性。这种行为被假设为Bi（III）的数量和位置对BizIn 2-zO 3-xOHy中的近端氢氧化物和配位不饱和金属表面位点的路易斯酸性和路易斯碱性的影响，其协同作用为受抑的路易斯酸碱对反应。本文报道的XPS在光催化反应器中，在黑暗和环境温度、150 ° C和150 ° C下，在光照射下，询问从真空状态过渡到类似条件的这种光化学RWGS反应。结合能位移被用来关联的材料系统的路易斯碱性响应这些酸性探针气体。原位气体电子灵敏度和原位UV-Vis衍生的带隙趋势证实了XPS结果中所示的趋势。低掺杂0.05%a.tBi体系的光催化还原CO_2与H_2的反应速率的提高与H_2 + CO_2的气敏性的提高有关，在热和光条件下，OH肩的增加比未掺杂的体系大得多。光诱导的OH肩的膨胀和增加的正结合能的位移显示了光照射的重要作用超过了热条件。高掺杂体系的催化性能差可归因于In 3+的竞争H2还原。结果提供了新的见解如何有条不紊地调整的路易斯酸和路易斯碱的表面挫折的路易斯酸碱对网站通过改变z量BizIn 2 O3-xOHy使光化学RWGS的速率的优化。
Characterization of Water Dissociation on $α$-Al$_{2}$O$_{3}$$(1\bar{1}02)$: Theory and Experiment
水与$α$ -氧化铝（即$α$-Al $_{2}$ O $_{3}$）表面的相互作用在各种应用中是重要的，并且是水与环境中丰富的铝硅酸盐相相互作用的有用模型.尽管其重要性，水与$α$ -Al $_{2}$ O $_{3}$表面而不是$(0001)$的相互作用的研究是非常有限的。在这里，我们表征的相互作用的水（D $_{2}$ O）与一个定义良好的$α$ -Al $_{2}$ O $_{3}$ $(1\bar{1}02)$表面在超高真空实验，使用程序升温脱附和表面特定的振动光谱，并在理论上，使用平板密度泛函理论计算。这种结合的方法使得有可能证明，水吸附只发生在一个单一的明确的表面位置（所谓的1-4配置），并在这个网站的分子和解离吸附形式之间的障碍是非常低的：0.06电子伏特。OD拉伸振动的子集平行于该解离坐标，因此预期相对于未耦合的谐振子被移位到低频。为了量化这种效应，我们沿着解离坐标求解振动薛定谔方程，发现基频红移超过1,500 cm $^{\text{-1}}$。在这个模型的上下文中，在中等温度下，我们进一步发现，表面氘核的一部分可能是离域的：解离和分子吸收状态不再是可区分的。
Many model potential energy surfaces (PESs) have been reported for water; however, none are strictly from "first principles". Here we report such a potential, based on a many-body representation at the CCSD(T) level of theory up to the ultimate 4-body interaction. The new PES is benchmarked for the isomers of the water hexamer for dissociation energies, harmonic frequencies, and unrestricted diffusion Monte Carlo (DMC) calculations of the zero-point energies of the Prism, Book, and Cage isomers. Dissociation energies of several isomers of the 20-mer agree well with recent benchmark energies. E…
We study NaCl ion-pair dissociation in a dilute aqueous solution using computer simulations both for the full system with long range Coulomb interactions and for a well chosen reference system with short range intermolecular interactions. Analyzing results using concepts from Local Molecular Field (LMF) theory and the recently proposed AI-based analysis tool "State predictive information bottleneck" (SPIB) we show that the system with short range interactions can accurately reproduce the transition rate for the dissociation process, the dynamics for moving between the underlying metastable sta…
Polyatomic molecules in strong laser fields can undergo substantial nuclear motion within tens of femtoseconds. Ion imaging methods based on dissociation or Coulomb explosion therefore have difficulty faithfully recording the geometry dependence of the field ionization that initiates the dissociation process. Here we compare the strong-field double ionization and subsequent dissociation of water (both H$_2$O and D$_2$O) in 10-fs and 40-fs 800-nm laser pulses. We find that 10-fs pulses turn off before substantial internuclear motion occurs, whereas rapid internuclear motion can take place durin…
