Selective alloy corrosion is used to synthesize a robust and ultrafine mesoporous NiFeMn-based metal/metal oxide oxygen evolving catalyst with ligament and pore sizes in the range of 10 nm and a BET surface area of 43 m.sup.2/g. As an oxygen evolving catalyst, the mesoporous catalyst exhibits high stability (>264 hours) at a high current density (500 mA/cm.sup.2) with a low overpotential (360 mV) using a moderate electrolyte concentration (1 M KOH). The catalyst is made from non-precious metals and its fabrication is straight forward and directly applicable to large-scale synthesis.

An exhaust gas-purifying catalyst includes a support and a catalytic metal as one or more precious metals supported by the support. The support includes a composite oxide having a composition represented by a general formula AB.sub.C.sub.O.sub.3, wherein A represents one or more elements selected from the group consisting of lanthanum, neodymium, and yttrium, B represents iron or a combination of iron and aluminum, C represents one or more elements selected from the group consisting of iridium, ruthenium, tantalum, niobium, molybdenum, and tungsten, and each represents a numerical value within a range of more than 0 and less than 1, and and satisfy relational formulae of > and +1.

An exhaust gas-purifying catalyst includes a support and a catalytic metal as one or more precious metals supported by the support. The support includes a composite oxide having a composition represented by a general formula AB.sub.C.sub.O.sub.3, wherein A represents one or more elements selected from the group consisting of lanthanum, neodymium, and yttrium, B represents iron or a combination of iron and aluminum, C represents one or more elements selected from the group consisting of iridium, ruthenium, tantalum, niobium, molybdenum, and tungsten, and each represents a numerical value within a range of more than 0 and less than 1, and and satisfy relational formulae of > and +1.

A porous metal-oxide composite particle suitable for use as a oxygen reduction reaction or oxygen evolution reaction catalyst and sacrificial support based methods for making the same.

A catalyst layer including: (i) a first catalytic material, wherein the first catalytic material facilitates a hydrogen oxidation reaction suitably selected from platinum group metals, gold, silver, base metals or an oxide thereof; and (ii) a second catalytic material, wherein the second catalytic material facilitates an oxygen evolution reaction, wherein the second catalytic material includes iridium or iridium oxide and one or more metals M or an oxide thereof, wherein M is selected from the group consisting of transition metals and Sn, wherein the transition metal is preferably selected from the group IVB, VB and VIB; and the first catalytic material is supported on the second catalytic material. The catalyst can be used in fuel cells, supported on electrodes or polymeric membranes for increasing tolerance to cell voltage reversal.

Tantalum nitride and specifically a novel Ta.sub.3N.sub.5 nanoparticles, such as single crystalline Ta.sub.3N.sub.5 nanoparticles, are disclosed. The nanoparticles used with a co-catalyst is further disclosed. The present invention also relates to Ta.sub.3N.sub.5 nanoparticles modified with a metal oxide, such as a CoO.sub.xcocatalyst, wherein O.sub.x represents an oxide that is part of the cobalt oxide. A catalyst, such as for water oxidation to produce O.sub.2, is disclosed. The nanoparticles can further be modified to include a water reducing catalyst. A water splitting catalyst is further disclosed. Methods of making the nanoparticles and catalyst are also disclosed. Methods to split water utilizing the catalyst are further described.

Disclosed herein are aspects of a method for converting an oxygenate feedstock into an olefin-rich product. In some aspects, the method comprises exposing an oxygenate feedstock to a tantalum catalyst composition to form an olefin-rich product. In some aspects, the tantalum catalyst composition comprises tantalum and a support comprising (i) aluminum and/or silicon, and (ii) oxygen.