Disclosed herein is a multi-layered composite thin film material formed from graphene quantum dots (GQDs) and metal nanocrystals in a layer-by-layer design, wherein the metal nanocrystals can be selected from the group consisting of Ru, Rh, Os, Ir, Pd, Au, Ag and Pt. In a preferred embodiment, the multi-layered composite thin film material is prepared via a facile, green, and easily accessible layer-by-layer (LbL) self-assembly strategy. In this strategy, positively charged GOQDs and negatively charged metal nanocrystals are alternately and uniformly integrated with each other in a “face-to-face” stacked fashion under substantial electrostatic attractive interaction, and then the obtained GOQDs/metal composite thin film is calcined into GQDs/metal composite thin film. The composite thin film material disclosed herein may be used to catalyse a wide range or reactions, including selective reduction of aromatic nitro compounds in water and electrocatalytic oxidation of methanol at ambient conditions.

An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a first washcoat region comprising platinum (Pt), manganese (Mn) and a first support material; a second washcoat region comprising a platinum group metal (PGM) and a second support material; and a substrate having an inlet end and an outlet end; wherein the second washcoat region is arranged to contact the exhaust gas at the outlet end of the substrate and after contact of the exhaust gas with the first washcoat region.

An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a first washcoat region comprising platinum (Pt), manganese (Mn) and a first support material; a second washcoat region comprising a platinum group metal (PGM) and a second support material; and a substrate having an inlet end and an outlet end; wherein the second washcoat region is arranged to contact the exhaust gas at the outlet end of the substrate and after contact of the exhaust gas with the first washcoat region.

A reduction catalyst body for carbon dioxide of an embodiment includes a metal layer, and a projection provided on the metal layer. The projection is constituted of an aggregate of fine metal particles, and possesses a polyhedral structure having surfaces of three faces or more of a polygon. The projection has a site of reducing carbon dioxide, as at least a part of the surfaces.

A reduction catalyst body for carbon dioxide of an embodiment includes a metal layer, and a projection provided on the metal layer. The projection is constituted of an aggregate of fine metal particles, and possesses a polyhedral structure having surfaces of three faces or more of a polygon. The projection has a site of reducing carbon dioxide, as at least a part of the surfaces.

A catalytic converter includes at least one heating element that is configured to disrupt the direction of flow of exhaust gases which contain harmful toxic gases and pollutants and aid in removing and/or reducing said toxic gases and pollutants.

A catalytic converter includes at least one heating element that is configured to disrupt the direction of flow of exhaust gases which contain harmful toxic gases and pollutants and aid in removing and/or reducing said toxic gases and pollutants.

A photocatalytic assembly (100) includes a substrate (110) and a photocatalytic unit (120) laminated on the substrate (110). The photocatalytic unit (120) includes a laminated titanium dioxide layer (122) and a metal layer (124). The titanium dioxide layer (122) has a thickness of 10 nm to 100 nm. The metal layer (124) is formed by stacking metal nanoparticles. The metal nanoparticle is made of at least one selected from the group consisting of rhodium, palladium, platinum, gold, silver, and aluminum.

A photocatalytic assembly (100) includes a substrate (110) and a photocatalytic unit (120) laminated on the substrate (110). The photocatalytic unit (120) includes a laminated titanium dioxide layer (122) and a metal layer (124). The titanium dioxide layer (122) has a thickness of 10 nm to 100 nm. The metal layer (124) is formed by stacking metal nanoparticles. The metal nanoparticle is made of at least one selected from the group consisting of rhodium, palladium, platinum, gold, silver, and aluminum.

The invention provides a process for preparing a methane oxidation catalyst comprising a mechanochemical treatment, a methane oxidation catalyst thus prepared and a method of oxidizing methane.