Novel layered solid oxide fuel cells with multiple-twinned Ni0.8Co0.2 nanoparticles: the key to thermally independent CO2 utilization and power-chemical cogeneration

Abstract

To energy-efficiently offset our carbon footprint, we herein developed a novel CH₄–CO₂ dry reforming process to co-produce electricity and CO-concentrated syngas, which takes advantage of the selective oxidation of H₂ in high performance proton-conducting solid oxide fuel cells (SOFCs). In these cells, an additional functional layer, consisting of a Ni_0.8Co_0.2–La_0.2Ce_0.8O_1.9 (NiCo–LDC) composite, was successfully incorporated into the anode support, forming a layered SOFC configuration. The multiple-twinned bimetallic nanoparticles were then proven to have superior activity towards in situ dry reforming. In comparison to the conventional design, this layered SOFC demonstrated drastically improved CO₂ resistance as well as internal reforming efficiency (CO₂ conversion reached 91.5% at 700 °C), and up to 100 h galvanostatic stability in a CH₄–CO₂ feedstream at 1 A cm⁻². More importantly, H₂ was effectively and exclusively converted by electrochemical oxidation, yielding no CO₂ but CO concentrated syngas in the anode effluent. The maximum power density exceeded 910 mW cm⁻² at 700 °C with a polarization resistance as low as 0.121 Ω cm². Consequently, the heat released by H₂ electrochemical oxidation fully compensated for that required by the extremely endothermic dry reforming reaction, making the entire process thermally self-sufficient. We also showed that the layered design was beneficial in terms of decreasing coking and increasing CO₂ resistance of the SOFC in the mixed CO₂ and CH₄ feedstock. This novel process promises to play a pivotal role in future CO₂ conversion and utilization.