The development of stable, efficient oxygen evolution reaction (OER) catalyst capable of oxidizing water is one of the premier challenges in the conversion of solar energy to electrical energy, because of its poor kinetics. Herein, a bipyridine-containing covalent organic framework (TpBpy) is utilized as an OER catalyst by way of engineering active Co­(II) ions into its porous framework. The as-obtained Co-TpBpy retains a highly accessible surface area (450 m2/g) with exceptional stability, even after 1000 cycles and 24 h of OER activity in phosphate buffer under neutral pH conditions with an overpotential of 400 mV at a current density of 1 mA/cm2. The unusual catalytic stability of Co-TpBpy arises from the synergetic effect of the inherent porosity and presence of coordinating units in the COF skeleton.

Covalent organic frameworks (COFs) have emerged as promising electrode materials in supercapacitors (SCs). However, their insoluble powder-like nature, poor capacitive performance in pristine form, integrated with inferior electrochemical stability is a primary concern for their long-term use in electrochemical devices. Keeping this in perspective, herein we report a redox active and hydrogen bonded COF with ultrahigh stability in conc. HSO (18 M), conc. HCl (12 M) and NaOH (9 M). The as-synthesized COF fabricated as thin sheets were efficiently employed as a free-standing supercapacitor electrode material using 3 M aq. HSO as an electrolyte. Moreover, the pristine COF sheet showcased outstanding areal capacitance 1600 mF cm (gravimetric 169 F g) and excellent cyclic stability (>100 000) without compromising its capacitive performance or Coulombic efficiency. Moreover, as a proof-of-concept, a solid-state supercapacitor device was also assembled and subsequently tested.

Here, we report a novel synthetic strategy to prepare a highly conducting polyethylenedioxythiphene (PEDOT) phase on flexible cellulose paper formed by inducing surfactant-free interfacial polymerization at the interface of two immiscible liquids. The illustrated process is highly scalable in such a way that very large flexible PEDOT paper can be prepared in 2-3 h under laboratory conditions. The obtained PEDOT-paper possesses efficiently packed π-conjugated chains and increased doping level which is proven by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and conductivity and UV-visble measurements. This favourable change has been attained by the slow polymerization coupled with the high dielectric constant of the interface, which stabilise the counter ions through hydrogen bonding. This helps for better inter-chain and intra-chain charge mobility, leading to conductivity as high as 375 S cm -1 compared to 30 S cm -1 of the PEDOT prepared in n-butanol. A low sheet resistance of 3 Ω/□ is achieved by multiple coating, which is found to be stable even after two months under ambient conditions and at various flexible and bending conditions. A flexible solid-state supercapacitor with an overall thickness of 0.17 mm made from the PEDOT paper and PVA-H 2 SO 4 as the solid electrolyte exhibits a volumetric energy density of 1 mWh cm -3 . The specific capacitance measured per mass of PEDOT in the system is 115 F g -1 along with a high volumetric capacitance of 145 F cm -3 . The above observed values are significantly higher compared to the bulk PEDOT tested on solid current collectors as well as highest among the literature reports. The flexible devices are found to be very stable during the charge-discharge cycling under twisted and bending conditions for more than 3800 cycles. A 3.6 V inter-digitized flexible device could also be made in a single PEDOT paper, which is found to be powered enough to glow an LED under flexible conditions.

Mechanochemically synthesized bipyridine based covalent organic framework showing high proton conductivity of 0.014 S cm−1 with improved performance over the solvothermal one giving a stable Open Circuit Voltage (0.93 V at 50 °C) on fabrication in PEM fuel cell.