The major challenge of photocatalytic water splitting, the prototypical reaction for the direct production of hydrogen by using solar energy, is to develop low-cost yet highly efficient and stable semiconductor photocatalysts. Herein, an effective strategy for synthesizing extremely active graphitic carbon nitride (g-C3N4) from a low-cost precursor, urea, is reported. The g-C3N4 exhibits an extraordinary hydrogen-evolution rate (ca. 20 000 μmol h−1 g−1 under full arc), which leads to a high turnover number (TON) of over 641 after 6 h. The reaction proceeds for more than 30 h without activity loss and results in an internal quantum yield of 26.5 % under visible light, which is nearly an order of magnitude higher than that observed for any other existing g-C3N4 photocatalysts. Furthermore, it was found by experimental analysis and DFT calculations that as the degree of polymerization increases and the proton concentration decreases, the hydrogen-evolution rate is significantly enhanced.

In this article, we experimentally investigate the substrate, wavelength, and time dependence of the plasmon-assisted surface-catalyzed dimerization of 4-nitrobenzenethiol to form p,p'-dimercaptoazobenzene on Au, Ag, and Cu films. We provide direct experimental evidence that surface plasmon resonance plays the most important role in these surface-catalyzed reactions. It is found that the reaction is strongly dependent on the substrate, the wavelength of the laser, and the reaction timescales. Our experimental results revealed that optimal experimental conditions can be rationally chosen to control (accelerate or restrain) this reaction. The experimental results are also confirmed by theoretical calculations.

The photooxidation of water using faceted Ag 3 PO 4 was investigated, guided by theoretical modelling.Firstly, theoretical calculations were performed to predict the optimum morphology for solar energy conversion by probing the surface energies of three primary low index facets of Ag 3 PO 4 : {100}, {110} and {111}. It was elucidated that the {111} facet possessed considerably higher surface energy (1.65 J m À2 ) than either {110} or {100} (0.78 and 0.67 J m À2 respectively). We therefore attempted to fabricate Ag 3 PO 4 crystals with {111} facets. Tetrahedral Ag 3 PO 4 crystals, composed of {111} facets, were then successfully synthesised using a novel kinetic control method in the absence of surfactants. In comparison to rhombic dodecahedron {110} and cubic {100} structures, tetrahedral crystals show an extremely high activity for water photooxidation, with an initial oxygen evolution rate exceeding 6 mmol h À1 g À1 , 10 times higher than either {110} or {100} facets. Furthermore, to the best of our knowledge it is the first time that the internal quantum yield for water photooxidation is almost unity at 400 nm, and greater than 80% from 365 to 500 nm, achieved by {111} terminated tetrahedrons. The excellent and reproducible performance is attributed to a synergistic effect between high surface energy and a small hole mass, leading to high charge carrier mobility and active surface reaction sites. Broader contextControlling the percentage of exposed facets on crystal surfaces can lead to a dramatic change in reactivity and also yield unique surface/bulk properties. Facet engineering has been demonstrated on certain photocatalysts with activity markedly improved. Very recently, visible light responsive photocatalysts, in particular Ag 3 PO 4 , have attracted much attention for their potential to meet the required efficiencies to produce clean renewable fuels. Using theoretical calculations, it was elucidated that the {111} facet possessed considerably higher surface energy than either {110} or {100}. Tetrahedral {111} Ag 3 PO 4 crystals were then synthesised using a novel kinetic control method. In comparison to {110} and {100} structures, {111} crystals show an extremely high activity for water photooxidation, with an initial oxygen evolution rate exceeding 6 mmol h À1 g À1 , 10 times higher than either {110} or {100} facets. The quantum yield for water photooxidation is almost unity at 400 nm using {111} crystals. The excellent and reproducible performance is attributed to a synergistic effect between high surface energy and a small hole mass. In a broader sense, the facile and green kinetic control method can be extended to the synthesis of other materials with preferred facets and is potentially an excellent candidate for incorporation into solar cells with a view to enhancing solar energy conversion.

In this paper, we report experimentally and theoretically a surface photocatalysis reaction of 4-aminothiophenol (PATP) to p,p 0dimercaptoazobenzene (DMAB) on Au, Ag, and Cu colloids. Surface enhanced Raman scattering (SERS) spectra of PATP on Au and Cu colloids are significantly different from the normal Raman spectrum of PATP powder. Quantum chemical calculations reveal that PATP on Au and Cu colloids is converted to DMAB by a surface photocatalysis reaction, and all the strongly enhanced Raman peaks are the symmetric Ag vibrational mode by surface plasmon. The pH value effects on surface photocatalysis reaction were also investigated experimentally. It is found that plasmon-assisted surface photocatalysis reaction can be efficiently controlled by different pH values. The possibility of protonation of PATP adsorbed on Au and Ag nanoparticles at pH 3 is investigated theoretically. The molecular mechanism is proposed for controlling surface photocatalysis reaction by pH values.

Storing hydrogen safely and efficiently is one of the major technological barriers preventing the widespread application of hydrogen-fueled cells, such as proton exchange membrane fuel cells (PEMFCs). Hydrous hydrazine (N 2 H 4 ·H 2 O) is considered as a promising liquid hydrogen storage material owing to the high content of hydrogen (7.9 %) and the advantage of CO-free H 2 produced. [1] In particular, hydrous hydrazine offers great potential as a hydrogen storage material for some special applications, such as unmanned space vehicles and submarine power sources, where hydrazine is usually used as a propellant.The decomposition of hydrazine proceeds by two typical reaction routes: [2] H 2 NNH 2 ! N 2 ðgÞ þ 2 H 2 ðgÞ ð 1Þ 3 H 2 NNH 2 ! 4 NH 3 ðgÞ þ N 2 ðgÞ ð 2ÞReaction (2) not only decreases the yield of H 2 but also complicates the separation process of products, because the ammonia by-product would poison the Nafion membrane and the fuel-cell catalysts. Thereby, it is of crucial importance to develop a highly selective catalyst over which the reaction proceeds only by pathway (1) at low temperatures. To this end, Xu and co-workers [3] synthesized a series of nickelcontaining bimetallic nanoparticles, including Ni-Rh, Ni-Pt, and Ni-Ir, which showed high H 2 selectivity at room temperature. Nevertheless, the incorporation of noble metals to nickel greatly increased the cost of catalysts. In a subsequent study by Xu and co-workers, [4] Ni-Fe nanoparticles were employed as catalysts for this reaction. However, the nanoparticles were only active at 70 8C, and addition of 0.5 mol L À1 NaOH was necessary for the high selectivity. Moreover, the practical application of colloidal nanoparticles will raise significant problems, such as mass production, handling, stability, separation, and recyclability. Therefore, from the viewpoint of practical applications, a supported base metal catalyst is a preferred choice owing to its low cost, good mechanical stability, and easy separation from the reaction medium.Herein, using a Ni-Al hydrotalcite-like compound (Ni-Al-HT) as the precursor, we obtained a highly dispersed nickel catalyst that presented 100 % conversion of N 2 H 4 ·H 2 O and up to 93 % selectivity to H 2 for the decomposition of N 2 H 4 ·H 2 O at ambient temperature. To our knowledge, this is the first report in which supported base metal catalysts show such high selectivity towards the formation of H 2 .It is well-known that supported noble metal catalysts, especially iridium catalysts, are very active for the decomposition of hydrazine. Compared with Ir, Ni is less active. [5] Accordingly, to obtain a high activity over Ni catalysts, a very high loading of Ni is required while maintaining a high degree of dispersion. Hydrotalcite-like compounds have been demonstrated to be excellent precursors for the preparation of highly dispersed and high-loading metal catalysts. [6] Herein, we synthesized binary Ni-Al-HT with interlayer CO 3 2À anions by a co-precipitation method. [7] After reduction in a H 2 atmosphere at...