Three-dimensional structurally complementary architecture enhancing the electrochemical activity and stability of protonic ceramic cells under intermediate-temperature multi-mode operation

Reversible protonic ceramic cells (RPCCs) are promising for bidirectional conversion between renewable electricity and chemical fuels, but their performance is limited by interfacial polarization, gas transport resistance, and structural instability at intermediate temperatures. Herein, a structurally complementary three-dimensional (3D) integrated architecture is developed, consisting of a dendritic NiO–BZCYYb fuel electrode, a dense BZCYYb electrolyte, and a 3D woven PBSCF air electrode. The coupling of macroscopic dendritic channels with microscopic fibrous networks extends active reaction interfaces, builds continuous proton-transport pathways, and promotes uniform interfacial reaction fields, thereby improving mass transfer, charge transport, and reaction kinetics. As a result, the integrated cell delivers enhanced performance in fuel-cell and steam-electrolysis modes, reduced operating voltage, improved CO₂ conversion during CO₂-assisted electrolysis, and stable operation under multiple working conditions. This work provides an effective 3D structural strategy for improving the activity, efficiency, and durability of RPCCs for CO₂ utilization and renewable fuel synthesis.