Cooler ceramic fuel cells: Ceramic ion conductors can be used as electrolytes in fuel cells using natural gas. One drawback of such solid-oxide fuel cells that conduct oxygen ions is their high operating temperatures (at least 600°C). Duan et al. have made a proton-conducting ceramic fuel cell with a modified cathode material that exhibits high performance on methane fuel at 500°C (see the Perspective by Gorte). Science , this issue p. 1321 ; see also p. 1290

BaCo _0.4 Fe _0.4 Zr _0.1 Y _0.1 O _3−δ is applied for the first time as a cathode for low-temperature solid oxide fuel cells (LT-SOFCs) with high power densities below 500 °C and 2500 hours stable performance.

The increasing global appetite for energy within the transportation sector will inevitably result in the combustion of more fossil fuel. A renewable-derived approach to carbon-neutral synthetic fuels is therefore needed to offset the negative impacts of this trend, which include climate change. In this communication we report the use of nonstoichiometric perovskite oxides in two-step, solar-thermochemical water or carbon dioxide splitting cycles. We find that LaAlO₃ doped with Mn and Sr will efficiently split both gases. Moreover the H₂ yields are 9× greater, and the CO yields 6× greater, than those produced by the current state-of-the-art material, ceria, when reduced at 1350 °C and re-oxidized at 1000 °C. The temperature at which O₂ begins to evolve from the perovskite is fully 300 °C below that of ceria. The materials are also very robust, maintaining their redox activity over at least 80 CO₂ splitting cycles. This discovery has profound implications for the development of concentrated solar fuel technologies.

A cost-effective solid-state reactive sintering (SSRS) method has recently been developed to synthesize high quality, fully dense, and large-grained yttrium-doped barium zirconate (BZY) ceramic pellets from the raw materials of BaCO₃, ZrO₂, Y₂O₃, and NiO, resulting in total proton conductivities as high as 3.3 × 10⁻² S·cm⁻¹at 600 °C under a wet argon atmosphere [J. Tong et al., Solid State Ionics, 2010, 181, 496]. In the present work, the mechanisms for the rapid formation of the cubic perovskite phase of BZY, pellet densification, and grain growth during SSRS synthesis are investigated in detail using a suite of experimental techniques. The pre-reaction addition of NiO to the precursor powders is confirmed to accelerate the formation of the cubic perovksite BZYphase. The rapid and full densification of NiO-modified pellets at relatively low temperature (1350 °C) is ascribed to the formation of the impure phase BaY₂NiO₅ and its subsequent role as a sintering aid. The dramatic further grain growth after densification is facilitated by the partial decomposition of the BaY₂NiO₅ (which is located primarily at grain boundaries) and its incorporation into the cubic perovskite structure of BZY.