Hydrogel Polymer-PBA Nanocomposite Thin Film-Based Bifunctional Catalytic Electrode for Water Splitting: The Unique Role of the Polymer Matrix in Enhancing the Electrocatalytic Efficiency

N-doped porous carbon with ZIF-67-derived CoFe2O4-Fe particles for supercapacitors

The development of novel materials for electrodes with high energy densities is essential to the advancement of energy storage technologies. In this study, N-doped layered porous carbon with ZIF-67-derived binary CoFe2O4-Fe particles was successfully fabricated by the pyrolysis of an Fe-based chitosan (CS) hydrogel mixed with ZIF-67 particles. Various characterization techniques were employed to assess the performance of the prepared porous CoFe2O4-Fe@NC composite. This composite exhibits excellent performance owing to the effective combination of multivalent CoFe2O4-Fe particles derived from ZIF-67 with N-doped porous carbon substances with a high surface area, which helps to accelerate ion and charge transfer. The specific capacitance of the CoFe2O4-Fe@NC composite carbonized at 700 °C reached 3960.9F/g at 1 A/g. When this composite is combined with activated carbon (AC) to construct an asymmetric supercapacitor (ASC), a density of energy of up to 84.9 W h kg-1 is attained at a power capacity of 291.6 W kg-1. Moreover, this composite maintained a capacitance retention of up to 94.9 % after 10,000 cycles. This work offers new perspectives on high-performance supercapacitors and their applications.

Sonication-Induced Boladipeptide-Based Metallogel as an Efficient Electrocatalyst for the Oxygen Evolution Reaction

Bioinspired, self-assembled hybrid materials show great potential in the field of energy conversion. Here, we have prepared a sonication-induced boladipeptide (HO-YF-AA-FY-OH (PBFY); AA = Adipic acid, F = l-phenylalanine, and Y = l-tyrosine) and an anchored, self-assembled nickel-based coordinated polymeric nanohybrid hydrogel (Ni-PBFY). The morphological studies of hydrogels PBFY and Ni-PBFY exhibit nanofibrillar network structures. XPS analysis has been used to study the self-assembled coordinated polymeric hydrogel Ni-PBFY-3, with the aim of identifying its chemical makeup and electronic state. XANES and EXAFS analyses have been used to examine the local electronic structure and coordination environment of Ni-PBFY-3. The xerogel of Ni-PBFY was used to fabricate the electrodes and is utilized in the OER (oxygen evolution reaction). The native hydrogel (PBFY) contains a gelator boladipeptide of 15.33 mg (20 mmol L-1) in a final volume of 1 mL. The metallo-hydrogel (Ni-PBFY-3) is prepared by combining 15.33 mg (20 mmol L-1) of boladipeptide (PBFY) with 3 mg (13 mmol L-1) of NiCl2·6H2O metal in a final volume of 1 mL. It displays an ultralow Tafel slope of 74 mV dec-1 and a lower overpotential of 164 mV at a 10 mA cm-2 current density in a 1 M KOH electrolyte, compared to other electrocatalysts under the same experimental conditions. Furthermore, the Ni-PBFY-3 electrocatalyst has been witnessed to be highly stable during 100 h of chronopotentiometry performance. To explore the OER mechanism in an alkaline medium, a theoretical calculation was carried out by employing the first-principles-based density functional theory (DFT) method. The computed results obtained by the DFT method further confirm that the Ni-PBFY-3 electrocatalyst has a high intrinsic activity toward the OER, and the value of overpotential obtained from the present experiment agrees well with the computed value of the overpotential. The biomolecule-assisted electrocatalytic results provide a new approach for designing efficient electrocatalysts, which could have significant implications in the field of green energy conversion.

An In Situ Fabricated Hydrogel Polymer - Palladium Nanocomposite Electrocatalyst for the HER: Critical Role of the Polymer in Realizing High Efficiency and Stability

Development of general and simple designs of catalytic electrodes for the hydrogen evolution reaction (HER) is critical. The present work demonstrates the multiple roles played by a hydrogel polymer in the fabrication and activity enhancement of the nanoelectrocatalyst. A nanocomposite thin film of Pd with the insulating hydrogel, poly(2-hydroxyethyl methacrylate) (PHEMA), is fabricated through a facile in situ process, the polymer itself functioning as the reducing/stabilizing agent in the formation of Pd nanoparticles. Pd-PHEMA on Ni foam enables efficient HER in alkaline medium with a low overpotential; the polymer enables the electrocatalysis by its swelling and confinement of the electrolyte. Most significantly, when the electrode is subjected to an optimized cycling protocol, the overpotential decreases steadily, reaching an impressively low value of 36 mV (@10 mA cm-2 ). A low Tafel slope (68 mV dec-1 ), high exchange current density, Faradaic efficiency and TOF (3.27 mA cm-2 , 99 %, 122.7 h-1 ), and extended stability are achieved. Detailed investigations reveal the active role of the polymer in the evolution of the nanocatalyst, itself undergoing favorable morphological changes. The study illustrates the widened scope for developing efficient and stable catalytic electrodes with hydrogel polymers and unique features that promote the generation of green hydrogen.

Plasma-assisted synthesis of hierarchical defect N-doped iron–cobalt sulfide@Co foam as an efficient bifunctional electrocatalyst for overall water splitting

N-doped CoFeS was synthesized via an ion exchange method to prepare a precursor, followed by sulphidation and plasma-assisted engraving in nitrogen gas.