Confined FeNi alloy nanoparticles in carbon nanotubes for photothermal oxidative dehydrogenation of ethane by carbon dioxide

Oxidative dehydrogenation of ethane with CO2 (ODEC) is an attractive reaction for reduction of carbon footprints and ethene production. In this work, we present photothermal catalysis on confined bimetal catalysts for ODEC. Carbon nanotubes confined non-noble bimetal alloy (i.e., CoNi@CNTs and FeNi@CNTs) catalysts were prepared and FeNi@CNTs showed effective performance in photothermal catalytic ODEC to ethene. Experiments and simulations reveal that UV and visible lights (420 – 490 nm) are responsible for ODEC and non-oxidative dehydrogenation of ethane, respectively, to ethene. Additionally, ODEC to ethene is preferred to C-C cracking to methane on FeNi@CNTs in light ( \u3e 490 nm)-induced thermocatalysis. The photothermal effect turns more significant when introduced into thermocatalytic ODEC (500 °C), with ethene generation at one order of magnitude. This work advances new mechanism of photo-mediated catalysis and sheds light on utilization of full-spectrum solar energy and non-noble metallic catalysts for ethene production and CO2 recycling at moderate conditions

Photo-thermo catalytic dry reforming of methane over Ni-Ir/SiO2 catalyst

Photo-thermo catalysis can effectively reduce the reaction temperature of dry reforming of methane (DRM) and increase the reaction efficiency. The development of a new type of high-efficiency photo-thermo catalyst and the exploration of its catalytic mechanism are the focuses of current research. A self-confinement strategy was used to prepare nickel-iridium bimetallic catalyst (Ni-Ir/SiO2). Catalyst physicochemical properties and photo-thermo catalytic performances on DRM were both studied. The results show that the bimetal nanoparticle has an average size of less than 3.5 nm and is evenly distributed on the substrate. The light absorption ability of the constructed ultra-small nickel-iridium bimetal is significantly enhanced. At the same time, the electrical field is also enhanced to effectively promote the hot electron excitation and realize its activation of methane and carbon dioxide molecules, especially their dissociation below the thermodynamic equilibrium temperature. In addition, the external heating of the system can further improve DRM reaction rate. Under the conditions of 700℃ and light intensity of 5 W/cm2, the H2 yield reaches 861 mmol/(g h), equivalent to that of the pure noble metal-based catalysts. Also, the catalyst shows good repeatability in the photo-thermo catalytic DRM reaction