Ti-substituted NH2-Uio-66(Zr/Ti) prepared by using a post-synthetic exchange (PSE) method showed enhanced photocatalytic performance for both CO2 reduction and hydrogen evolution under visible light. Density functional theory (DFT) calculations and electron spin resonance (ESR) results reveal that the introduced Ti substituent acts as a mediator to facilitate electron transfer, which results in enhanced performance.

of semiconductor photocatalysts to retard the recombination of charge carriers and enhance surface reaction rates. [13][14][15] Among various kinds of cocatalysts, Pt often shows the best performance. However, practical application of Pt-based cocatalysts is limited by their scarcity and high cost. [16] Therefore, development of highly active and cost-efficient alternatives to Pt is urgently needed. A large number of transition metals (e.g., iron, cobalt, nickel, molybdenum, and tungsten) and their derivative compounds have been studied. Fu and colleagues have integrated CdS with MoS 2 and obtained much improved hydrogen evolution activity. [17] However, the performances of which are still far from satisfactory because of the low active surface areas and sluggish separation of electron-hole pairs. [18][19][20] Thus, designing novel materials which can address these problems may lead to the discovery of non-noble metal cocatalysts with enhanced performance. Metal oxide clusters, constructed by a small number of atoms, can largely expose active metal sites. [21] Moreover, when loaded onto semiconductor photocatalysts, metal oxide clusters can induce discrete energy bands to trap charge carriers and promote the separation of electrons and holes. Regarding such unique properties, cluster cocatalysts show the potential to boost the activity of semiconductor photocatalysts for solar water splitting.The performance of cluster cocatalysts is significantly influenced by the number and coordination environment of the active atoms. [22][23][24] Therefore, it is essential to establish a synthetic method to precisely control the configuration of clusters decorated on the surface of semiconductor photocatalysts at atomic level. [25,26] Herein, a bottom-up strategy is developed to decorate ultrasmall molybdenum-oxygen (MoO x ) clusters onto the surface of CdS nanowires (NWs). The decorated clusters with finely controlled size and configuration greatly enhance the photocatalytic H 2 evolution efficiency of CdS NWs.CdS NWs are first synthesized through a solvothermal approach. [27] X-ray diffraction (XRD) pattern of as-prepared sample shows characteristic peaks of CdS with hexagonal wurtzite crystal structure ( Figure S1, Supporting Information). Field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and high-resolution TEM (HRTEM) images indicate the successful synthesis of CdS NWs with good crystallinity (Figure S2, Supporting Information). The average diameter of the CdS NWs is about 75 nm (Figure S3, Supporting Information). MoO x clusters are then decorated To enhance the performance of semiconductor photocatalysts, cocatalysts are used to accelerate surface reactions. Herein, ultrasmall molybdenumoxygen (MoO x ) clusters are developed as a novel non-noble cocatalyst, which significantly promotes the photocatalytic hydrogen generation rate of CdS nanowires (NWs). As indicated by extended X-ray absorption fine structure analysis, direct bonds are formed between CdS NWs and MoO x clusters,...

A cocatalyst is necessary for boosting the electron-hole separation efficiency and accelerating the reaction kinetics of semiconductors. As a result, it is of critical importance to in situ track the structural evolution of the cocatalyst during the photocatalytic process, but it remains very challenging. Here, atomically dispersed Ru atoms are decorated over multi-edged TiO2 spheres for photocatalytic hydrogen evolution. Experimental results not only demonstrate that the photogenerated electrons can be effectively transferred to the isolated Ru atoms for hydrogen evolution but also imply that the TiO2 architecture with multi-edges might facilitate the charge separation and transport. The change in valence and the evolution of electronic structure of Ru sites are well probed during the photocatalytic process. Specifically, the optimized catalyst produces the hydrogen evolution rate of 7.2 mmol g−1 hour−1, which is much higher than that of Pt-based cocatalyst systems and among the highest reported values.

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A series of zirconium polyphenolate-decorated-(metallo)porphyrin metal-organic frameworks (MOFs), ZrPP-n (n = 1, 2), featuring infinite Zr -oxo chains linked via polyphenolate groups on four peripheries of eclipse-arranged porphyrin macrocycles, are successfully constructed through a top-down process from simulation to synthesis. These are the unusual examples of Zr-MOFs (or MOFs in general) based on phenolic porphyrins, instead of commonly known carboxylate-based types. Representative ZrPP-1 not only exhibits strong acid resistance (pH = 1, HCl) but also remains intact even when immersed in saturated NaOH solution (≈20 m), an exceptionally large range of pH resistance among MOFs. The metallation at the porphyrin core gives rise to materials with enhanced sorption and catalytic properties. In particular, ZrPP-1-Co, with precise and uniform distribution of active centers, exhibits not only high CO trapping capability (≈90 cm g at 1 atm, 273 K, among the highest in Zr-MOFs) but also high photocatalytic activity for reduction of CO into CO (≈14 mmol g h ) and high selectivity over CH (>96.4%) without any cocatalyst under visible-light irradiation (λ > 420 nm). Given the strong chemical resistance under extreme alkali conditions, these catalysts can be recycled without appreciable loss of activity. The possible mechanism for photocatalytic reduction of CO -to-CO over ZrPP-1-Co is also proposed.