A novel carbon cycle process assisted by Ni/La_(2)O_(3) catalyst for enhanced thermochemical CO_(2) splitting

Thermochemical two-step CO_(2) splitting is a potential approach that fixes the sustainable resource into transportable liquid fuels.However,the harsh CO_(2) splitting conditions,the limited oxygen release kinetics and capacity of metal oxides block further promoted the CO yield and solar-to-fuel energy efficiency.Here,we propose a different carbon cycle assisted by Ni/La_(2)O_(3) via coupling methane decomposition with thermochemical CO_(2) splitting,replacing conventional metal oxides cycle.Superior performance was demonstrated with methane conversion reached around 94%with almost pure H_(2) generation.Encouragingly,CO_(2) conversion of 98%and CO yield of 6.9 mmol g^(-1) derived from CO_(2) were achieved,with peak CO evolution rate(402 mL min^(-1) g^(-1))of orders of magnitude higher than that in metal oxide process and outstanding thermodynamic solar-to-fuel energy efficiency(55.5%vs.18.5%).This was relevant to the synergistic activation of La_(2)O_(3) and Ni for CO_(2) in carbon cycle,thus improving CO_(2) splitting reaction with carbon species.

Intensified solar thermochemical CO_(2) splitting over iron-based redox materials via perovskite-mediated dealloying-exsolution cycles

Solar thermochemical CO_(2)-splitting(STCS)is a promising solution for solar energy harvesting and storage.However,practical solar fuel production by utilizing earth-abundant iron/iron oxides remains a great challenge because of the formation of passivation layers,resulting in slow reaction kinetics and limited CO_(2)conversion.Here,we report a novel material consisting of an iron-nickel alloy embedded in a perovskite substrate for intensified CO production via a two-step STCS process.The novel material achieved an unprecedented CO production rate of 381 mL g^(-1)min^(-1)with 99%CO_(2)conversion at 850℃,outperforming state-of-the-art materials.In situ structural analyses and density functional theory calculations show that the alloy/substrate interface is the main active site for CO_(2)splitting.Preferential oxidation of the FeNi alloy at the interface(as opposed to forming an FeO_(x)passivation shell encapsulating bare metallic iron)and rapid stabilization of the iron oxide species by the robust perovskite matrix significantly promoted the conversion of CO_(2)to CO.Facile regeneration of the alloy/perovskite interfaces was realized by isothermal methane reduction with simultaneous production of syngas(H_(2)/CO=2,syngas yield>96%).Overall,the novel perovskite-mediated dealloying-exsolution redox system facilitates highly efficient solar fuel production,with a theoretical solar-to-fuel efficiency of up to 58%,in the absence of any heat integration.