Perovskites as substitutes of noble metals for heterogeneous catalysis: dream or reality.

Nanocrystalline calcium phosphate ceramics in biomedical engineering

Rational design of efficient, stable oxygen evolution reaction (OER) catalysts is necessary for widespread adoption of electrochemical energy storage technologies. Achieving this goal requires elucidation of fundamental relationships between surface structure and reaction mechanism. Here we address this issue using ab initio computations to determine the surface structure and OER mechanism for LaNiO3, a perovksite oxide that exhibits high activity but low stability. We find a new OER mechanism in which lattice oxygen participation via reversible formation of surface oxygen vacancies is critical. We show that this mechanism has a lower reaction barrier compared to the generally proposed mechanism, leading to improved agreement with experimental data. Extending the study to La1–xSrxBO3 (B = transition metal), we demonstrate a transition to the lattice oxygen-mediated mechanism with decreasing catalyst stability. Our results suggest new approaches for next-generation catalysts design.

A Fundamental Relationship between Reaction Mechanism and Stability in Metal Oxide Catalysts for Oxygen Evolution

http://ms.sit.edu.cn/picture/article/120/cc/09/bfaa57df4a72a85b5be6a43a00b9/6174eb71-4f3c-408c-b04a-b4270adcb4fd.pdf

Glycine–nitrate combustion synthesis of CuO–ZnO–ZrO2 catalysts for methanol synthesis from CO2 hydrogenation

Combustion synthesis of CuFe2O4

Combustion synthesis of calcium aluminates

Combustion synthesis of iron-substituted strontium titanate perovskites

La (1 – x)
NiO
 (3 – δ)
 perovskites present high metallic conductivity and Pauli-paramagnetism, and could be used as electrodes in electrochemical devices such as SOFCs, PEMFCs and MCFCs. Additionally, due to its σ* conducting band, this material shows a very high electrocatalytic activity, particularly in oxygen reduction processes, with an efficiency comparable to that of platinum. This work describes the combustion synthesis of La (1 – x)
NiO
 (3 – δ)
 perovskite powders (x = 0 and 0.1) from mixtures of La(NO
 3
)
 3
·6H
 2
O and Ni(NO
 3
)
 2
·6H
 2
O as cation precursors, and urea as fuel. The as-prepared combustion product, characterized by XRD, DTA/TG, SEM/TEM, BET and dilatometry (after compaction), shows a much higher specific surface area than powders obtained via alternative routes and contains La 2
NiO
 4
 with a typical K
 2
NiF
 4
-type structure, together with small amounts of NiO. The usual subsequent heat treatments for 1 to 12 h at successively higher temperatures showed that full conversion to La (1 – x)
NiO
 (3 – δ)
 can be readily achieved in air at 750 °C and that the perovskite, after the 12 h heat treatment, remains stable up to 1100 °C. These results show that the combustion technique is a better and much simpler route to the synthesis of perovskite powders.

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Non-stoichiometric La(1 – x)NiO(3 – δ) perovskites produced by combustion synthesis

/pdf/effect-of-silica-fume-additions-on-the-hydration-behaviour-49przlrq1z.pdf

Daniel A. Fumo

Papers

Combustion synthesis of calcium aluminates

Combustion synthesis of iron-substituted strontium titanate perovskites

Non-stoichiometric La(1 – x)NiO(3 – δ) perovskites produced by combustion synthesis

Effect of silica fume additions on the hydration behaviour of calcium aluminates