Reticulated porous structures of La0.8Al0.2NiO3-δ perovskite for enhanced green hydrogen production by thermochemical water splitting

Abstract

The preparation and optimisation of La0.8Al0.2NiO3-δ (LANi82) perovskite shaped as reticulated porous ceramic (RPC) structures for H2 production by thermochemical water splitting is presented for the first time. The perovskite was first synthesised in powder form following a modified Pechini method. The redox properties of the LANi82 were first tested under N2/air flow in a thermogravimetric analyser. After that, the sponge replica method for preparing RPCs was optimised in terms of slurry composition and final thermal treatment to obtain a LANi82-RPC structure with porosity and strength appropriate to enhance heat and mass transfer in further solar reactors. The optimised LANi82-RPC material showed an outstanding hydrogen production of 8.3 cm3 STP/gmaterial·cycle at isothermal conditions (800 °C). This production was increased up to 11.5 cm3 STP/gmaterial·cycle if the thermal reduction was performed at 1000 °C. Additionally, a stable activity with almost constant H2 production in consecutive cycles was obtained for the optimised LANi82-RPC in both cases. The structure of the reticulated porous materials, with open macroporosity and wide interconnected channels, enhances heat and mass transfer, leading to higher hydrogen productions of the LANi82-RPC as compared to the materials as powder form in the same experimental set-up. These facts reinforce the favourable prospects of LANi82-RPC for large-scale hydrogen production, improving the coupling to current solar thermal concentration technologies developed, such as concentrated solar power tower.