BET theory

About: BET theory is a research topic. Over the lifetime, 9046 publications have been published within this topic receiving 286142 citations.

Mesoporous Ni60Fe30Mn10-alloy based metal/metal oxide composite thick films as highly active and robust oxygen evolution catalysts

Abstract: A major challenge in the field of water electrolysis is the scarcity of oxygen-evolving catalysts that are inexpensive, highly corrosion-resistant, suitable for large-scale applications and able to oxidize water at high current densities and low overpotentials. Most unsupported, non-precious metals oxygen-evolution catalysts require at least ∼350 mV overpotential to oxidize water with a current density of 10 mA cm−2 in 1 M alkaline solution. Here we report on a robust nanostructured porous NiFe-based oxygen evolution catalyst made by selective alloy corrosion. In 1 M KOH, our material exhibits a catalytic activity towards water oxidation of 500 mA cm−2 at 360 mV overpotential and is stable for over eleven days. This exceptional performance is attributed to three factors. First, the small size of the ligaments and pores in our mesoporous catalyst (∼10 nm) results in a high BET surface area (43 m2 g−1) and therefore a high density of oxygen-evolution catalytic sites per unit mass. Second, the open porosity facilitates effective mass transfer at the catalyst/electrolyte interface. Third and finally, the high bulk electrical conductivity of the mesoporous catalyst allows for effective current flow through the electrocatalyst, making it possible to use thick films with a high density of active sites and ∼3 × 104 cm2 of catalytic area per cm2 of electrode area. Our mesoporous catalyst is thus attractive for alkaline electrolyzers where water-based solutions are decomposed into hydrogen and oxygen as the only products, driven either conventionally or by photovoltaics.

Nano-Au/CeO2 catalysts for CO oxidation: Influence of dopants (Fe, La and Zr) on the physicochemical properties and catalytic activity

Abstract: The present investigation was undertaken to know the influence of different dopants on the physicochemical properties and catalytic behavior of nano-Au/CeO2 catalyst for CO oxidation. Accordingly, various metal ions namely, Fe3+, La3+ and Zr4+ were incorporated into the ceria lattice by a facile coprecipitation approach using ultra-high dilute aqueous solutions. An anion adsorption method was used to prepare the Au/doped-CeO2 catalysts in the absence of any base, reducing and protective agents. The physicochemical characterization was performed by XRD, BET surface area, ICP-AES, TG-DTA, FT-IR, TEM, UV–vis DRS, Raman, XPS and TPD techniques. Doped CeO2 exhibited smaller crystallite size, higher BET surface area and larger amount of oxygen vacancies than the pure CeO2. These remarkable properties showed a beneficial effect toward gold particle size as confirmed by XRD and TEM studies. XPS results revealed that Au is present in the metallic state and Ce in both +3 and +4 oxidation states. Incorporation of Zr into the Au/CeO2 resulted in high CO oxidation activity attributed to the presence of more Ce3+ ions and oxygen vacancies. In contrast, the La-incorporation caused an opposite effect due to the presence of carbonate species on the surface of Au/CeO2–La2O3 catalyst, which blocked the active sites essential for CO oxidation. It was shown that accumulation of carbonate species strongly depends on the acid–base properties of the supports. The catalytic performance of Au catalysts is highly dependent on the nature of the support.