ZnO/ZnGaNO heterostructure with enhanced photocatalytic properties prepared from a LDH precursor using a coprecipitation method

In this study, relationships between preparation conditions, structure, and activity of Pt-containing TiO₂ photocatalysts in photoinduced reforming of glycerol for H₂ production were explored. Commercial Aerolyst® TiO₂ (P25) and homemade TiO₂ prepared by precipitation-aging method were used as semiconductors. Pt co-catalysts were prepared by incipient wetness impregnation from aqueous solution of Pt(NH₃)₄(NO₃)₂ and activated by calcination, high temperature hydrogen, or nitrogen treatments. The chemico-physical and structural properties were evaluated by XRD, ¹H MAS NMR, ESR, XPS, TG-MS and TEM. The highest H₂ evolution rate was observed over P25 based samples and the H₂ treatment resulted in more active samples than the other co-catalyst formation methods. In all calcined samples, reduction of Pt occurred during the photocatalytic reaction. Platinum was more easily reducible in all of the P25 supported samples compared to those obtained from the more water-retentive homemade TiO₂. This result was related to the negative effect of the adsorbed water content of the homemade TiO₂ on Pt reduction and on particle growth during co-catalyst formation.

https://www.mdpi.com/1996-1944/11/10/1927/pdf

Study of PtOx/TiO2 Photocatalysts in the Photocatalytic Reforming of Glycerol: The Role of Co-Catalyst Formation

Graphite-oxide/TiO2 (GO/TiO2) composite materials were prepared by heterocoagulation method from Brodie’s graphite-oxide (GO) in order to test them as catalysts in the methanol photocatalytic reforming reaction in liquid phase. The preparation of the composite itself resulted in only little changes in the structure of GO as it was indicated by attenuated total reflection infrared (ATR-IR) and 13C magic-angle spinning nuclear magnetic resonance (13C MAS NMR) spectroscopic measurements. However, during the photocatalytic reaction, all of the GO/TiO2 samples darkened strongly indicating structural changes of GO. X-ray photoelectron spectroscopy along with NMR confirmed the loss of oxygen functionalities and emergence of graphitic species in the samples recovered from the photocatalytic reaction. Model experiments were designed to identify the key factors determining the activity of the GO/TiO2 derived photocatalysts. It was found that the emergence of a pronounced coupling between TiO2 and the graphite-like carbonaceous material is the most important contribution to get active and stable photocatalysts.

/pdf/graphite-oxide-tio2-nanocomposite-type-photocatalyst-for-2i6av00pmm.pdf

Graphite Oxide-TiO2 Nanocomposite Type Photocatalyst for Methanol Photocatalytic Reforming Reaction

Recently, metal nitrides (MNs) have received renewed attention due to their potential as catalytic materials in energy transformations, with water spitting and CO2 reduction being the most studied reactions Reactions considered in this review are limited to photocatalysis Moreover, the morphology, size, defects and nanostructured construction of MNs are demonstrated to be critical factors in their catalytic efficiency, emphasizing the importance of their synthetic method Mono, binary, ternary and doped nanostructured MN materials have been synthesized and evaluated as photocatalysts The latest research is focused on the development of new synthetic methods, cocatalysts, and constructure design, aiming to achieve improved activity, selectivity, and stability This review provides a broad overview of the development of photocatalysts for the generation of H2 and CO2 reduction reaction, summarizing the current state of work focusing on the recent progress in light-induced overall water splitting and CO2 reduction on metal nitride photocatalysts

Nanostructured metal nitrides for photocatalysts

A versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc-gallium oxynitrides and zinc-gallium-indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well-defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2  g-1 ). X-ray diffraction studies show that the final material is not a mixture of single oxides but a distinctive compound. The photocatalytic properties of the oxynitrides have been tested towards the decomposition of an organic dye (as a model reaction for the decomposition of air pollutants), showing better photocatalytic performances than the corresponding pure phases (reaction constant 0.22 h-1 ), whereas almost no reaction was observed in absence of catalyst or in the dark. The photocatalysts have been also tested for H2 evolution (semi-reaction of the water splitting process) with results comparable to the best literature values but leaving room for further improvement.

/pdf/multimetallic-oxynitrides-nanoparticles-for-a-new-generation-1g8di87x5r.pdf

ÿdám Vass

Papers

Structural evolution in Pt/Ga-Zn-oxynitride catalysts for photocatalytic reforming of methanol