Remarkable chemical adsorption of CO2 has been achieved in titanate with significant concentration of oxygen vacancies towards the efficient direct CO2 electrolysis in solid oxide electrolysers.

This paper presents a ceramic composite oxygen electrode (La 0.75 Sr 0.25 ) 0.95 Mn 0.5 Cr 0.5 O 3-δ (LSCM) -BaCe 0.5 Zr 0.3 Y 0.16 Zn 0.04 O 3-δ (BCZYZ) for steam electrolysis in a proton-conducting Solid Oxide Electrolyzer (SOE) with proton conducting electrolyte BCZYZ and fuel electrode BCZYZ/Ni at 700 • C. AC impedance spectroscopy and I-V tests demonstrate two main processes from 0 to 2 V with 3%H 2 O/N 2 vs 5% H 2 /Ar: reoxidation of the LSCM electrode below 1.2 V and oxidation of H 2 O above 1.2 V. The current density reaches 2 Acm −2 at 2 V with electrode polarization of 0.1 cm 2 and steam electrolysis shows short term stability with current efficiency of 22%.Hydrogen is regarded as the leading candidate fuel because it has the potential to address the environmental and energy security issues associated with fossil hydrocarbon fuels. 1-5 Natural gas reforming is currently a main way for massive hydrogen production, but still relies on fossil fuel consumption. 6 Water electrolysis capable of producing hydrogen is still far away to its real application because of the huge electricity consumption for water splitting. 7 On the contrary, steam electrolysis is more promising as the high temperature heat partly offers the energy for steam dissociation and then leads to favorable kinetics and thermodynamics. [8][9][10][11] Proton conducting solid oxide electrolysis cells (SOECs) as the reverse mode of proton conducting Solid Oxide Fuel Cells (SOFCs) have attracted considerable attention because they are able to operate in high efficiency in conjunction with renewable electricity and to effectively exploit available heat streams (such as exhaust heat from nuclear plant). 12-15 They can efficiently produce pure hydrogen through high-temperature steam electrolysis. In this process, steam is oxidized in the oxygen electrode and simultaneously split into oxygen and proton under external electrolysis potential. Protons diffuse across the proton conducting electrolyte to the fuel electrode where the formation of pure hydrogen from protons takes place in the three-phase boundary. The formation of hydrogen only takes place in fuel electrode compartment, which makes it unnecessary to separate hydrogen from steam.The oxygen electrode is under strongly oxidizing condition in steam electrolysis, which hence a pure redox active metal is not able to work. It is therefore necessary to develop an appropriate oxygen electrode with high catalytic activity and low over potentials. The perovskite (La 0.75 Sr 0.25 ) 0.95 Mn 0.5 Cr 0.5 O 3-δ (LSCM) is an active and redox stable material which has attracted a lot of attention in SOFCs 16-24 and can hereby be considered as a good oxygen electrode material candidate. High-performance Pervoskite-type ceramic BaCe 0.5 Zr 0.3 Y 0.16 Zn 0.04 O 3-δ (BCZYZ) is adopted as electrolyte in this work because it has been recently proven to be an excellent proton conductor with good chemical stability, high proton conductivity as well as low sintering temperature. 25 In this work, a composite oxygen e...

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850-750 C in humidified hydrogen, better than or comparable to the best ceramic anodes in the literature.