Photocatalytic reduction of dinitrogen to ammonia over noble-metal-loaded TiO2
TL;DR: The photocatalytic reduction of dinitrogen to ammonia is influenced by the nature and amount of metal loading on TiO2 and the optimum metal content varies depending on the nature of the metal as mentioned in this paper.
Abstract: The photocatalytic reduction of dinitrogen to ammonia is influenced by the nature and amount of metal loading on TiO2. The optimum metal content varies depending on the nature of the metal. A correlation between the ammonia yield and the intermediary MH bond strength is established (low bond strength gives rise to low ammonia yield).
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TL;DR: In this article, a surfactant mediated sol-gel method was employed to synthesize bismuth silicate heterostructures with tunable morphologies and properties, which exhibited excellent photodegradation against malachite green and rhodamine B dyes in the aqueous medium.
18 citations
TL;DR: In this article, a Cu2O quantum dot/graphene-TiO2 composite was successfully synthesized using a facile hydrothermal method, and the reaction was used to load the CU2O and TiO2 particles.
Abstract: A Cu2O quantum dot/graphene-TiO2 composite, a novel material, was successfully synthesized using a facile hydrothermal method. The hydrothermal reaction was used to load the Cu2O and TiO2 particles...
16 citations
Cites background from "Photocatalytic reduction of dinitro..."
...phenomenon promises to improve the catalytic activity of the Cu2O-graphene-TiO2 composite (34,35)....
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References
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TL;DR: In this paper, the dependence of the exchange current for the electrolytic evolution of hydrogen on metals (i 0,H ) on the work function is analyzed on the basic of a new list of polycrystalline surfaces.
1,474 citations
TL;DR: The photolysis of chemisorbed water on incompletely outgassed TiO/sub 2/ powder yields H 2 and O 2 in the molar ratio of 2 : 1 if conducted under argon in the presence of molecular nitrogen as mentioned in this paper.
Abstract: The photolysis of chemisorbed water on incompletely outgassed TiO/sub 2/ powder yields H/sub 2/ and O/sub 2/ in the molar ratio of 2 : 1 if conducted under argon In the presence of molecular nitrogen, O/sub 2/ is still formed but the evolution of H/sub 2/ is inhibited as chemisorbed nitrogen is reduced to NH/sub 3/ and traces of N/sub 2/H/sub 4/ according to N/sub 2/ + 3H/sub 2/O + nhv yields 2NH/sub 3/ + 150/sub 2/ and N/sub 2/ + 2H/sub 2/O + mhv yields N/sub 2/H/sub 4/ + O/sub 2/ Iron doping enhances the photocatalytic reactivity of rutile and provides prototypes of solar cells for photochemical ammonia synthesis from N/sub 2/ and H/sub 2/O
817 citations
TL;DR: In this article, the improvement of H/sub 2/ evolution from two different types of catalytic p-type photocathode surfaces has been examined, and a comparison of the naked p-Si, the simply platinized, and the (PQ/sup 2 +//sup ///sup +/.)sub n/.nPt(0))/sub surf/ system compared to the same surface directly platinised confirm an important difference in the mechanism of H /sub 2 / evolution catalysis for the two surface catalyst systems.
Abstract: The improvement of H/sub 2/ evolution from two different types of catalytic p-type photocathode surfaces has been examined. p-Type Si has been platinized by phtotelectrochemically plating Pt(0) onto the Si surface. Such a photocathode shows significant improvement (compared to naked p-type Si) for photochemical H/sub 2/ evolution with respect to output photovoltage, fill factor, and overall efficiency. Such photocathodes having an optimun amount of Pt(0) give a pH-dependent output voltage with respect to the H/sub 2/O/H/sub 2/ couple, but the dependence is not a simple 59-mV/pH dependence. No pH dependence would be expected if Pt(0) formed a Schottky barrier when plated onto p-type Si. A second kind of H/sub 2/ evolution catalyst has been confined to the surface of p-type Si. Polymeric quantities of an electroactive N,N'-dialkyl-4,4'-bipridinium reagent, (PQ/sup 2 +/.)/sub n/, have been confined to the surface. The Br/sup -/ counterions of the polymer are then exchanged by PtCl/sub 6//sup 2 -/. Photoreduction then yields Pt(0) dispersed in the polymer. Such a surface is again significantly improved compared to naked p-type Si with respect to H/sub 2/ evolution. A comparison of the naked p-Si, the simply platinized, and the (PQ/sup 2 +//sup ///sup +//sub n/.nPt(0))/sub surf./ system is mademore » and contrasted to the expected behavior of an external Schottky barrier photocell driving an electrolysis cell with a Pt cathode. Experiments with n-type MoS/sub 2/, n-type Si, Pt, Au, and W cathodes functionalized with the (PQ/sup 2 +//sup ///sup +/.)sub n/.nPt(0))/sub surf./ system compared to the same surface directly platinized confirm an important difference in the mechanism of H/sub 2/ evolution catalysis for the two surface catalyst systems. p-Type Si modified with optimum amounts of Pt(0) by direct platinization appears to give improved H/sub 2/ evolution efficiency by a mechanism where the Pt(0) serves as a catalyst that does not alter the interface energetics of the semiconductor.« less
318 citations
TL;DR: The quantum yield of hydrogen production was increased greatly by supporting metals or metal complexes on the TiO2 surface, amounting to 38% for a Pt-TiO2 photocatalyst.
218 citations
TL;DR: In this paper, the Fermi level difference of p-InP and H/sup +//H/sub 2/ (0.9 +/- 0.2 eV) was shown to be a function of metal work functions.
Abstract: Noble metal incorporation in the surface of p-type semiconductor photocathodes to catalyze hydrogen evolution leads to efficient solar to chemical conversion if a set of energetic and kinetic criteria are satisfied: (1) the semiconductor-catalyst junction barrier height must be equal to or greater than that of the semiconductor H/sup +//H/sub 2/ junction; (2) the recombination velocity of photogenerated electrons at the semiconductor-catalyst interface must be low; (3) the overpotential for hydrogen evolution at solar cell current densities (approx.30 mA/cm/sup 2/) must be minor. Because of substantial differences in the vacuum work functions of Pt, Rh, Ru, and the (redox potential of the) H/sup +//H/sub 2/ couple, the barrier heights for junctions of each of the four systems with p-InP ought to vary widely. Yet experiments show that all p-InP(M)/H/sup +//H/sub 2/ junctions, where M = Pt, Rh, Ru, or no metal, have essentially the same approx.0.7-V gain in onset potential for hydrogen evolution relative to Pt/H/sup +//H/sub 2/. We attribute the similarity to the known lowering of metal work functions upon hydrogen alloying. Such alloying increases the barrier height and thereby the gain in onset potential over that anticipated from the vacuum work functions. The barrier height, measured as themore » limiting value of onset potential gain at high irradiance, approaches in all cases the Fermi level difference of p-InP and H/sup +//H/sub 2/ (0.9 +/- 0.2 eV). That Fermi level pinning by interfacial states is not the cause of the similar barriers is evident from the reversible decrease in onset potential with hydrogen depletion and by a unity diode perfection factor of the p-InP(Rh)/H/sup +//H/sub 2/ photocathode, which indicates no measurable interfacial recombination of photogenerated carriers. In agreement, the quantum efficiency of carrier collection (hydrogen evolution) nears unity.« less
184 citations