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In developing countries and resource-limited regions, where no power infrastructure is available, photothermal-driven membrane distillation (PMD) has been recognized as an attractive and sustainable technology for freshwater generation.

A major limitation for polymeric mixed ionic/electronic conductors (MIECs) is the trade-off between ionic and electronic conductivity; changes made that improve one typically hinder the other. In order to address...

Direct borohydride fuel cells (DBFCs) can operate at double the voltage of proton exchange membrane fuel cells (PEMFCs) by employing an alkaline NaBH 4 fuel feed and an acidic H 2 O 2 oxidant feed. The pH-gradient-enabled microscale bipolar interface (PMBI) facilitates the creation and maintenance of an alkaline environment at the anode and an acidic environment at the cathode for the borohydride oxidation and peroxide reduction reactions. However, given the need to dissociate water at the interface to ensure ionic conduction, PMBI can be efficient only when anion exchange ionomer (AEI) moieties enable fast water transport for autoprotolysis. Herein, a series of polynorbornene-based AEIs with a range of water uptake values are examined to unravel the optimum water uptake required to enable high performance DBFCs. The DBFC with PMBI configuration containing the optimal AEI composition delivers a current density of 302 mA cm −2 at 1.5 V and a peak power density of 580 mW cm −2 at 1 V. This AEI composition exhibits high hydroxide ionic conductivity of 90.7 mS cm −1 at 80 °C with an IEC of 2.01 mequiv g −1 and demonstrates impressive chemical stability by retaining 98.75% of its initial ionic conductivity after immersion into anolyte (3 M KOH and 1.5 M NaBH 4 ) at 70 °C for 536 h.

Cost-effective and highly active borohydride oxidation reaction (BOR) electrocatalysts are crucial for the advancement of direct borohydride fuel cells (DBFCs). Noble-metal electrocatalysts, such as Pd, are used as benchmark electrocatalysts because of their superior BOR activity. However, Pd suffers from catalyst poisoning because of strong binding with BH x intermediates at a high BOR overpotential, making it unsuitable for high DBFC performance, whereas Ni exhibits a low degree of catalyst poisoning because of a relatively weak binding of BH x intermediates. Density functional theory (DFT) calculations indicate a lowering of H-and OH-binding energies on bimetallic PdNi surfaces in comparison to their individual counterparts, thereby freeing more sites for BH 4 adsorption that is crucial for a high BOR rate. The as-synthesized bimetallic PdNi/C electrocatalyst exhibits higher current densities at a BH 4 concentration range of 50−500 mM than Pd/C and Ni/C. A DBFC unit with a pH-gradientenabled microscale bipolar interface employing PdNi/C, Pt/C, and H 2 O 2 as the anode, cathode, and oxidant, respectively, exhibits a power density of 466 ± 1.5 mW/cm 2 at 1.5 V, a peak power density of 630 ± 2 mW/cm 2 at 1.1 V, with an open-circuit voltage of 1.95 ± 0.01 V. Our bimetallic alloy electrocatalyst shows high DBFC performance, providing a pathway for the development of suitable BOR electrocatalysts.

Due to its unmatched theoretical voltage of 2.18 V, direct alkaline fuel cell using sodium borohydride solution at the anode and hydrogen peroxide at the cathode, represents a promising power...

No abstract

The alkaline stability of functional cations tethered to anion exchange membranes (AEMs) is essential for long-term operation in electrochemical devices. Here, we report the use of AEMs with pure aliphatic polymer backbones containing N-spirocyclic quaternary ammonium cation groups as highly conductive, crosslinked, and reinforced separators. Synthesizing these pure aliphatic-based AEMs via irradiation with ultraviolet (UV) light at room temperature avoids the use of carcinogenic solvents and the solution casting step generally used in AEM preparation. The resultant aliphatic-based AEMs have a chloride ion conductivity of 82 mS cm−1 at 70 °C with an ion exchange capacity (IEC) of 3.0 ± 0.2 mmol g−1. The aliphatic-based AEM retains 40% of its initial IEC after immersion in 1 M KOH at 80 °C for 30 d. A direct nucleophilic substitution degradation mechanism is proposed for such AEMs, based on FT-IR, solid state 13C-NMR spectroscopy, and XPS.