Recently, semiconductor-ionic materials (SIMs) have emerged as new functional materials, which possessed high ionic conductivity with successful applications as the electrolyte in advanced low-temperature solid oxide fuel cells (LT-SOFCs). In order to reveal the ion-conducting mechanism in SIM, a typical SIM pellet consisted of semiconductor La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and ionic conductor Sm and Ca Co-doped ceria Ce0.8Sm0.05Ca0.15O2-δ (SCDC) are suffered from sintering at different temperatures. It has been found that the performance of LSCF-SCDC electrolyte fuel cell decreases with the sintering temperature, the cell assembled from LSCF-SCDC pellet sintered at 600 °C exhibits a peak power density (Pmax) of 543 mW/cm2 at 550 °C and also excellent performance of 312 mW/cm2 even at LT (500 °C). On the contrary, devices based on 1000 °C pellet presented a poor Pmax of 106 mW/cm2. The performance difference may result from the diverse ionic conductivity of SIM pellet through different temperatures sintering. The high-temperature sintering could severely destroy the interface between SCDC and LSCF, which provide fast transport pathways for oxygen ions conduction. Such phenomenon provides direct and strong evidence for the interfacial conduction in LSCF-SCDC SIMs.

Recently, the multifunctional semiconductor CeO₂ realized high ionic conductivity via surface conduction and delivered higher fuel cell performance. This indicates a promising strategy for the design of an electrolyte for the low-temperature ceramic fuel cell. In this study, we develop a ceria-based electrolyte by surface doping Bi into CeO₂ to attain the CeBiO₂ (BDC) electrolyte. The designed electrolyte is facilitated with an enriched O-vacancy surface layer, enabling high ionic conduction (0.20 S/cm) and excellent power density (1057 mW/cm²) at 530 °C. The difference in the Fermi level of BDC and CeO₂ arises due to the surface doping, which entails the band alignment and establishes the space charge region, thereby constituting a built-in field enhancing the charge transportation and minimizing e-conduction. In order to assist the formation of O-vacancies in the design, the BDC electrolyte density functional theory calculation was also made. These findings suggest surface doping is the best approach to attaining excellent performance and designing electrolytes and electrodes for advanced low-temperature fuel cell technology.

Water scarcity has emerged as an intense global threat to humanity and needs prompt attention from the scientific community. Solar-driven interfacial evaporation and seawater desalination are promising strategies to resolve the primitive water shortage issue using renewable resources. However, the fragile solar thermal devices, complex fabricating techniques, and high cost greatly hinder extensive solar energy utilization in remote locations. Herein, we report the facile fabrication of a cost-effective solar-driven interfacial evaporator and seawater desalination system composed of carbon cloth (CC)-wrapped polyurethane foam (CC@PU). The developed solar evaporator had outstanding photo-thermal conversion efficiency (90%) with a high evaporation rate (1.71 kg m⁻² h⁻¹). The interfacial layer of black CC induced multiple incident rays on the surface allowing the excellent solar absorption (92%) and intensifying heat localization (67.37 °C) under 1 kW m⁻² with spatially defined hydrophilicity to facilitate the easy vapor escape and validate the efficacious evaporation structure using extensive solar energy exploitation for practical application. More importantly, the long-term evaporation experiments with minimum discrepancy under seawater conditions endowed excellent mass change (15.24 kg m⁻² in consecutive 8 h under 1 kW m⁻² solar irradiations) and promoted its operational sustainability for multi-media rejection and self-dissolving potential (3.5 g NaCl rejected from CC@PU surface in 210 min). Hence, the low-cost and facile fabrication of CC@PU-based interfacial evaporation structure showcases the potential for enhanced solar-driven interfacial heat accumulation for freshwater production with simultaneous salt rejection.