Hydrogen evolution reaction (HER) by electrochemical water splitting is one of the most active areas of energy research, yet the benchmark electrocatalysts used for this reaction are based on expensive noble metals. This is a major bottleneck for their large‐scale operation. Thus, development of efficient metal‐free electrocatalysts is of paramount importance for sustainable and economical production of the renewable fuel hydrogen by water splitting. Covalent organic frameworks (COFs) show much promise for this application by virtue of their architectural stability, nanoporosity, abundant active sites located periodically throughout the framework, and high electronic conductivity due to extended π‐delocalization. This study concerns a new COF material, C6‐TRZ‐TFP, which is synthesized by solvothermal polycondensation of 2‐hydroxybenzene‐1,3,5‐tricarbaldehyde (TFP) and 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tris[(1,1′‐biphenyl)‐4‐amine]. C6‐TRZ‐TFP displayed excellent HER activity in electrochemical water splitting, with a very low overpotential of 200 mV and specific activity of 0.2831 mA cm−2 together with high retention of catalytic activity after a long duration of electrocatalysis in 0.5 m aqueous H2SO4. Density functional theory calculations suggest that the electron‐deficient carbon sites near the π electron‐donating nitrogen atoms are more active towards HER than those near the electron‐withdrawing nitrogen and oxygen atoms.

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The limited stock of classical nonrenewable energy sources has motivated researchers to explore efficient strategies for sustainable and renewable energy production. Hydrogen production via electrochemical water splitting is one of the key solutions that can meet this demand. Today 3d transition metal based nanomaterials offer a huge opportunity in the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we report an easy and convenient synthesis route for designing the novel tetradentate phosphonate ligand based metal–organic framework (MOF, H8L-Co-crystal). The material has been characterized by single crystal X-ray diffraction (SXRD), powder XRD, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, and explored in the HER from various mediums including seawater. This single crystal belongs to the monoclinic phase having C2/c space group, with unit cell parameters a = 29.364(8) (Å), b = 12.204(4) (Å), c = 9.925(3) (Å), α = 90° = γ, β = 97.405° (CCDC no. 1922964) and the unit cell volume = 3527.04 Å3. The material H8L-Co-crystal shows very good catalytic activity towards H2 evolution with a low overpotential of 243 mV at a current density 10 mA/cm2 as well as a low Tafel slope of 102 mV/dec in acidic medium, which is comparable to commercial HER catalysts, and one of the best among non-postsynthetically modified MOFs. The electrochemical active surface area (ECSA) data have been measured to explain the high hydrogen evolution rate in different mediums. Density functional theory (DFT) study based on first-principle calculations provides a very useful understanding about the structure–catalytic property relationship and reveals the role of surface active sites toward electrochemical HER.

Development of an efficient and robust material for adsorptive removal of highly toxic metals like mercury from water resources is very challenging from the perspectives of hygiene and sustainable environment....

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Developing a robust metal‐organic framework (MOF) which facilitates proton hopping along the pore channels is very demanding in the context of fabricating an efficient proton‐conducting membrane for fuel cells. Herein, we report the synthesis of a novel tetradentate aromatic phosphonate ligand H8L (L=tetraphenylethylene tetraphosphonic acid) based Ni‐MOF, whose crystal structure has been solved from single‐crystal X‐ray diffraction. Ni‐MOF [Ni2(H4L)(H2O)9(C2H7SO)(C2H7NCO)] displays a monoclinic crystal structure with a space group of P 21/c, a=11.887 Å, b=34.148 Å, c=11.131 Å, α=γ=90°, β=103.374°, where a nickel‐hexahydrate moiety located inside the void space of the framework through several H‐bonding interactions. Upon treatment of the Ni‐MOF in different pH media as well as solvents, the framework remained unaltered, suggesting the presence of strong H‐bonding interactions in the framework. High framework stability of Ni‐MOF bearing H‐bonding interactions motivated us to explore this metal‐organic framework material as proton‐conducting medium after external proton doping. Due to the presence of a large number of H‐bonding interactions and the presence of water molecules in the framework we have carried out the doping of organic p‐toluenesulfonic acid (PTSA) and inorganic sulphuric acid (SA) in this Ni‐MOF and observed high proton conductivity of 5.28×10−2 S cm−1 at 90 °C and 98% relative humidity for the SA‐doped material. Enhancement of proton conductivity by proton doping under humid conditions suggested a very promising feature of this Ni‐MOF.

A novel biocompatible COF, TRIPTA is used as a drug delivery carrier for cisplatin in TNBC cells. It delivered cisplatin effectively, which inhibited the proliferation and migration of TNBC cells by increasing the cytotoxicity of cisplatin.

Exploring a covalent organic framework (COF) material as an efficient metal-free photocatalyst and as an adsorbent for the removal of pollutants from contaminated water is very challenging in the context of sustainable chemistry. Herein, we report a new porous crystalline COF, C6-TRZ-TPA COF, via segregation of donor–acceptor moieties through the extended Schiff base condensation between tris(4-formylphenyl)amine and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)trianiline. This COF displayed a Brunauer–Emmett–Teller (BET) surface area of 1058 m2 g–1 with a pore volume of 0.73 cc g–1. Again, extended π-conjugation, the presence of heteroatoms throughout the framework, and a narrow band gap of 2.2 eV, all these features collectively work for the environmental remediation in two different perspectives: it could harness solar energy for environmental clean-up, where the COF has been explored as a robust metal-free photocatalyst for wastewater treatment and as an adsorbent for iodine capture. In our endeavor of wastewater treatment, we have conducted the photodegradation of rose bengal (RB) and methylene blue (MB) as model pollutants since these are extremely toxic, are health hazard, and bioaccumulative in nature. The catalyst C6-TRZ-TPA COF showed a very high catalytic efficiency of 99% towards the degradation of 250 parts per million (ppm) of RB solution in 80 min under visible light irradiation with the rate constant of 0.05 min–1. Further, C6-TRZ-TPA COF is found to be an excellent adsorbent as it efficiently adsorbed radioactive iodine from its solution as well as from the vapor phase. The material exhibits a very rapid iodine capturing tendency with an outstanding iodine vapor uptake capacity of 4832 mg g–1.