Polymer electrolyte membrane fuel cells (PEMFCs) expect a promising future in addressing the major problems associated with production and consumption of renewable energies and meeting the future societal and environmental needs. Design and fabrication of new proton exchange membranes (PEMs) with high proton conductivity and durability is crucial to overcome the drawbacks of the present PEMs. Acid-doped polybenzimidazoles (PBIs) carry high proton conductivity and long-term thermal, chemical, and structural stabilities are recognized as the suited polymeric materials for next-generation PEMs of high-temperature fuel cells in place of Nafion^® membranes. This paper aims to review the recent developments in acid-doped PBI-based PEMs for use in PEMFCs. The structures and proton conductivity of a variety of acid-doped PBI-based PEMs are discussed. More recent development in PBI-based electrospun nanofiber PEMs is also considered. The electrochemical performance of PBI-based PEMs in PEMFCs and new trends in the optimization of acid-doped PBIs are explored.

Perovskite solar cells (PSCs) have captured the attention of the global energy research community in recent years by showing an exponential augmentation in their performance and stability. The supremacy of the light-harvesting efficiency and wider band gap of perovskite sensitizers have led to these devices being compared with the most outstanding rival silicon-based solar cells. Nevertheless, there are some issues such as their poor lifetime stability, considerable J–V hysteresis, and the toxicity of the conventional constituent materials which restrict their prevalence in the marketplace. The poor stability of PSCs with regard to humidity, UV radiation, oxygen and heat especially limits their industrial application. This review focuses on the in-depth studies of different direct and indirect parameters of PSC device instability. The mechanism for device degradation for several parameters and the complementary materials showing promising results are systematically analyzed. The main objective of this work is to review the effectual strategies of enhancing the stability of PSCs. Several important factors such as material engineering, novel device structure design, hole-transporting materials (HTMs), electron-transporting materials (ETMs), electrode materials preparation, and encapsulation methods that need to be taken care of in order to improve the stability of PSCs are discussed extensively. Conclusively, this review discusses some opportunities for the commercialization of PSCs with high efficiency and stability.

Proton exchange membrane fuel cells (PEMFCs) cathode catalysts’ robustness is one of the primary factors determining its long-term performance and durability. This work presented a new class of corrosion-resistant catalyst, Magnél TiO₂ supported Pt (Pt/Ti₉O₁₇) composite, synthesized. The durability of a Pt/Ti₉O₁₇ cathode under the PEMFC operating protocol was evaluated and compared with the state-of-the-art Pt/C catalyst. Like Pt/C, Pt/Ti₉O₁₇ exhibited exclusively 4e⁻ oxygen reduction reaction (ORR) in the acidic solution. The accelerated stress tests (AST) were performed using Pt/Ti₉O₁₇ and Pt/C catalysts in an O₂-saturated 0.5 M H₂SO₄ solution using the potential-steps cycling experiments from 0.95 V to 0.6 V for 12,000 cycles. The results indicated that the electrochemical surface area (ECSA) of the Pt/Ti₉O₁₇ is significantly more stable than that of the state-of-the-art Pt/C, and the ECSA loss after 12,000 potential cycles is only 10 ± 2% for Pt/Ti₉O₁₇ composite versus 50 ± 5% for Pt/C. Furthermore, the current density and onset potential at the ORR polarization curve at Pt/C were significantly affected by the AST test. In contrast, the same remained almost constant at the modified electrode, Pt/Ti₉O₁₇. This demonstrated the excellent stability of Pt nanoparticles supported on Ti₉O₁₇.

Rare earth elements (REEs) extraction via conventional technologies is exceedingly energy and environmentally intensive. New efficient and sustainable technologies for REE extraction from primary and secondary resources would be extremely beneficial. This research demonstrated a novel low-temperature electrochemical extraction process for extracting REEs from lignite coal ash (LCA) solutions. The LCA contained 17 different REEs with a concentration ranging from 13 to 1645 ppm. The LCA solution mixed with ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate (BMITF) was used for extracting REEs at different electrochemical potentials. The ICP-MS analysis confirmed an overall 26% REEs recovery from the LCA solution with 16 out of the 17 REEs successfully extracted from the LCA solution. This study shows an environmentally benign and energy-efficient REE extraction process that is suitable for coal and coal byproducts.