The contribution of water molecules to the hydrogen evolution reaction

Traditionally,water molecules act as solvents in most chemical reactions,whereas they act as solvents and reactants in the alkaline electrolyte for the hydrogen evolution reaction(HER).It is well known that there is a current plateau in the linear potential–current dependence for HER in neutral or near-neutral electrolytes,showing that the HER is governed by the mass transport of reactive hydronium species at a given overpotential.The sharp rise in the current signal after the plateau at a sligh...     

光催化制氢中助催化剂表面氢氧复合反应的抑制

在光催化分解水产氢的过程中,Pt等助催化剂在催化产生氢的同时也会诱导催化氢气和氧气重新复合为水的逆反应,严重降低了悬浮体系光催化全分解水产氢的效率。本文综述了近年来在逆反应抑制方面的研究进展,总结和对比分析了各种抑制逆反应策略的特点,并对这些方法的应用于悬浮体系光催化全分解水制氢的前景进行了展望。     

Electron attachment to clusters composed of closed shell,hydrogen containing molecules

Electron attachment to clusters of HCl, H₂O, D₂O, C₂H₄(OH)₂, NH₃, and ND₃ is compared. The clusters are produced in a seeded supersonic beam traversing a sustained gas discharge. For the first four moleculesN _min=2 is the lowest number of molecules necessary to support a bound negative ion state. A much largerN _min and an isotope effect is observed for ammonia,N _min(NH₃)=35, andN _min(ND₃)=41.     

Diironhexacarbonyl clusters with imide and amine ligands: hydrogen evolution catalysts

The reaction of Fe₃(CO)₁₂ and N-(4-thiolphenyl)-1,8-naphthalimide afforded a new diironhexacarbonyl complex (3). The integrity and electronic structure of 3 has been determined by elemental analysis and spectroscopy (NMR and infrared). Infrared spectrum of 3 shows peaks at 2000, 2040, and 2075?cm^?1 ascribed to stretching frequencies of the terminal metal carbonyls. Compound 4 was obtained from the reaction of Fe₃(CO)₁₂ and 4-aminothiolphenol. A comparison of the electronic, electrochemical, and electrocatalytic properties of 3 and 4 are discussed. Cyclic voltammetric studies show that 3 and 4 catalyze the reduction of acetic acid to produce hydrogen at ?2.19?V and ?1.88?V versus Fc/Fc⁺, respectively.     

Blocking backward reaction on hydrogen evolution cocatalyst in a photosystem II hybrid Z-scheme water splitting system

Photocatalytic Z-scheme water splitting is considered as a promising approach to produce solar hydrogen. However, the forward hydrogen production reaction is often impeded by backward reactions. In the present study, in a photosystem II-integrated hybrid Z-scheme water splitting system, the backward hydrogen oxidation reaction was significantly suppressed by loading a PtCrOx cocatalyst on a ZrO₂/TaON photocatalyst. Due to the weak chemisorption and activation of molecular hydrogen on PtCrOx, where Pt is stabilized in the oxidized forms, Pt^II and Pt^IV, hydrogen oxidation is inhibited. However, it is remarkably well-catalyzed by the metallic Pt cocatalyst, thereby rapidly consuming the produced hydrogen. This work describes an approach to inhibit the backward reaction in the photosystem II-integrated hybrid Z-scheme water splitting system using Fe(CN)₆^3?/Fe(CN)₆^4? redox couple as an electron shuttle.     

Co porphyrin-based metal-organic framework for hydrogen evolution reaction and oxygen reduction reaction

Constructing molecule@support composites is an attractive strategy to realize heterogeneous molecular electrocatalysis. Herein, we synthesized metal-organic framework (MOF)-supported molecular catalysts for hydrogen evolution and oxygen reduction reaction (HER/ORR). Ligand exchange strategy was used to prepare molecule@support hybrids due to the same functional group. A series of hybrids were obtained using Co porphyrin (1) and different MOFs including MIL-88(Fe), MOF-5(NiCo) and UIO-66(Zr). The 1@MOF-5(NiCo) had the best HER and ORR activity compared with 1@MIL-88(Fe) and 1@MOF-5(NiCo). These hybrids also exhibited tunable selectivity for ORR with four-electron process, which can be attributed to the synergistic effect of porphyrin molecules and MOFs. This work provides a possibility for molecular catalysts to improve activity of HER and tune selectivity of ORR.     

Lattice-confined Ru clusters for hydrogen oxidation reaction with high CO-tolerance

正Hydrogen has been considering as a promising renewable energy source and a viable alternative for fossil-fuels in the future [1,2]. Hydrogen oxidation reaction (HOR) and its reverse reaction are two significant reactions for applying hydrogen as electrochemical energy. On the other hand,platinum is believed to be the best electrocatalyst for HOR,although several drawbacks including high cost, scarcity,low CO tolerance, and depressed catalytic activities in alkaline environments, hinder the development of hydrogen application [1]. Hence, it is highly desired to develop Pt-free HOR catalysts with high activity, high stability, low cost, and good resistance to CO poisoning [3].     

Viologen-modified platinum clusters acting as an efficient catalyst in photocatalytic hydrogen evolution

A highly efficient photocatalytic system for hydrogen evolution with dihydronicotinamide coenzyme (NADH) as a sacrificial agent in an aqueous solution has been constructed by using water-soluble platinum clusters functionalized with methyl viologen-alkanethiol (MVA2+) and a simple electron-donor dyad, 9-mesityl-10-methylacridinium ion (Acr+-Mes), which is capable of fast photoinduced electron transfer but extremely slow back electron transfer. The mean diameter of the platinum core was determined as R(CORE) = 1.9 nm with a standard deviation sigma = 0.5 nm by transmission electron microscopy (TEM). As a result, the hydrogen-evolution rate of the photocatalytic system with MVA2+-modified platinum clusters (MVA2+-PtC) is 10 times faster than the photocatalytic system with the mixture of the same amount of MVA2+ and platinum clusters as that of MVA2+-PtC under otherwise the same experimental conditions. The radical cation of NADH has been successfully detected by laser flash photolysis experiments. The decay of the absorbance due to NAD*, produced by the deprotonation from NADH*+, coincides with the appearance of the absorption band due to Acr*-Mes. This indicates electron transfer from NAD* to Acr+-Mes to give Acr*-Mes, which undergoes the electron-transfer reduction of MVA2+-PtC, leading to the efficient hydrogen evolution.     

层状过渡金属氢氧化物应用于碱性氢气析出反应（英文）

氢气因为其高质量比活性,环境友好等特点,被公认为是一种很有希望替代化石能源的可再生能源.其中,碱性条件电解水被认为是可大规模生产氢气的技术之一.但氢气析出反应在碱性条件反应速率缓慢,为提升氢气析出反应速率,因此研究者们设计和制备了大量的材料.本文归纳了有效促进碱性条件氢气析出反应速率的关键材料——层状过渡金属氢氧化物的重要研究进展.首先,基于过渡金属氢氧化物的结构,阐述了过渡金属氢氧化物与氢气析出反应活性材料间的协同催化机理.接着,以提升协同催化作用为中心,归纳了基于过渡金属氢氧化物的氢气析出反应催化剂和电极的最近研究进展,分别包含过渡金属氢氧化物和氢气析出反应活性材料的种类、结构、形貌及其相互作用.此外,本文从高活性和长寿命的催化剂和电极设计出发,归纳了最近基于过渡金属氢氧化物的催化剂和电极在水分解领域的进展.最后,本文总结和展望了电解水制氢技术的未来应用和发展中不可避免的一些问题与挑战.目前,应用于氢析出反应的过渡金属氢氧化物主要集中于镍基、钴基和铁基氢氧化物和其双金属氢氧化物,为层状水滑石结构.因为上述过渡金属氢氧化物弱的氢吸附,所以其析氢活性非常低.但是过渡金属氢氧化物对氢氧根...     

Theoretical study of hydrogen bonded clusters of water and fulminic acid

Ab initio and density functional calculations are used to analyze the interaction between a molecule of fulminic acid with 1, 2, 3, and 4 molecules of water along with a 2:2 complex at B3LYP/6-31+G(d,p) and MP2/6-311++G(d,p) computational levels. Cooperative effect (CE) in terms of stabilization energy of clusters are calculated and discussed as well. CE is increased with increasing cluster size of studied clusters. Red shifts of H–C stretching frequency for complexes involving HCNO as H-donor are predicted.     

Photoinduced dissociation of water and transport of hydrogen between silver clusters

Theoretical electronic structure calculations are reported for the dissociation of water adsorbed on a 31-atom silver cluster, Ag31, and subsequent transfer of a H to a second Ag31 cluster leaving OH on the first cluster. Both ground and excited electronic state processes are considered for two choices of Ag cluster separation, 6.35 and 7.94 A, on the basis of preliminary calculations for a range of separation distances. The excited electronic state of interest is formed by photoemission of an electron from one Ag cluster and transient attachment of the photoemitted electron to the adsorbed water molecule. A very large energy barrier is found for the ground-state process (3.53 eV at a cluster separation of 6.35 A), while the barrier in the excited state is small (0.38 eV at a cluster separation of 6.35 A). In the excited state, partial occupancy of an OH antibonding orbital facilitates OH stretch and concomitant movement of the negatively charged OH toward the electron-hole in the metal cluster. The excited-state pathway for dissociation of water and transfer of H begins with the formation of an excited electronic state at 3.59-3.82 eV. Stretch of the OH bond occurs with little change in energy (0.38-0.54 eV up to a stretch of 1.96 A). In this region of OH stretch the molecule must return to the ground-state potential energy surface to fully dissociate and to transfer H to the other Ag cluster. Geometry optimizations are carried out using a simplex algorithm and a semigrid method. These methods allow the total energy to be calculated directly using configuration interaction theory.     

Molecular solid solution of lanthanide-titanium-oxo clusters with enhanced photocatalytic hydrogen evolution

Molecular solid solutions of metal clusters containing different metal centers with well-defined structures can accurately regulate the HOMO-LUMO gap,but are rarely available.Herein,a series of colorless lanthanide-titanium-oxo clusters Ln₂Ti₄(μ₂-O)₂(μ₃-O)₄(Piv)₁₀(THF)₂(Ln₂Ti₄,Ln = Eu,Gd,Tb,and Ce,HPiv = pivalic acid) were synthesized by the reaction of pivalic acid with Ln(Ac)₃     

Rational design of Ru species on N-doped graphene promoting water dissociation for boosting hydrogen evolution reaction

In this study,the morphological distribution of Ru on nitrogen-doped graphene (NG) could be rationally regulated via modulating the combination mode between Ru precursor and the zeolite imidazolate framework-8 (ZIF-8).The cation exchange and host-guest strategies respectively resulted in two different combination modes between Ru precursor and ZIF-8 anchored on graphene.Following pyrolysis of the above precursors,Ru single-atom sites (SASs) with and without Ru nanoparticles (NPs)were formed sele...     

Electron attachment to HCl clusters

Negatively charged cluster ions of hydrogen chloride are formed by electron attachment to HCl clusters, which are produced in a seeded supersonic beam traversing a sustained gas discharge. Cluster ions of (HCl) _n ^? , withn=2, and tentatively withn=3 and 4 are observed. Cluster ions like Cl _n ^? , Cl _n ^? (HCl) _m , and withAr attached to them are also seen. The relevance to radiation chemistry of HCl if briefly discussed. Atoms evaporating from the hot, thoriated tungsten filament of the glow discharge lead to clusters such as Th _n ^? and its oxides.     

Copper phthalocyanine complex as electrocatalyst for hydrogen evolution reaction

In this work, we have sought economically viable methods for hydrogen evolution reaction (her). For this purpose, we have investigated the voltammetric and in situ spectroelectrochemical behavior of copper phthalocyanine complex and its electrocatalytic activity for her. In spite of the belief that the complexes bearing redox active metal center can catalyze hydrogen evolution reactions, copper phthalocyanine having ring-based redox processes shows excellent electrocatalytic activity.     

Acridinium salts as metal-free electrocatalyst for hydrogen evolution reaction

Here we report the purely organic metal-free electrocatalyst — acridinium salt 9-phenyl-10-methylacridinium iodide for hydrogen evolution reaction. A controlled potential electrolysis experiment in present 9-phenyl-10-methylacridinium iodide with a simultaneous gas chromatographic analysis confirmed the catalytic production of molecular hydrogen. The behavior of the catalytic wave is typical for a “total catalysis”. A mechanism involving initial reduction of PhAcr⁺/PhAcr and subsequent protonation is proposed.     

Phase engineering two-dimensional nanostructures for electrocatalytic hydrogen evolution reaction

Hydrogen(H₂) is considered to be a promising substitute for fossil fuels. Two-dimensional(2D) nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly, phase engineering of 2D nanomaterials is opening a novel research direction to endow 2D nanostructures with fascinating properties for deep applications in catalyzing HER. In this review, we briefly summarize the research progress and present the current challenges on...     

Electrocatalytic properties of cobalt-molybdenum alloy deposits in the hydrogen evolution reaction

Electrocatalytic activity of cobalt-molybdenum deposits is studied in the hydrogen evolution reaction (HER) in an alkaline solution. The studied electrode materials were obtained electrochemically in the galvanostatic mode. It is shown that the rate of hydrogen evolution in 1 M NaOH at 293 K at the Co-Mo alloy is higher, as compared to pure cobalt deposits obtained in similar conditions, which is due both to the increase of the electrode true surface area and possibly to the electronic structure of the obtained alloys. It is established that the hydrogen reaction exchange current grows at the increase of molybdenum content in the electrode deposits in the range of 0–40 at %.