Metal-free catalysis for electrocatalytic hydrogen evolution from water is very demanding for the production of sustainable and clean fuel. Herein, we report the synthesis of a porphyrin-based metal-free covalent organic polymer (TpPAM) through a simple condensation between triformyl phloroglucinol (Tp) and 5,10,15,20-tetra(4-aminophenyl)-21H,23H-porphyrin (PAM). The as-prepared porous TpPAM exhibited superior activity for the hydrogen evolution reaction (HER) current density of 10 mA cm −2 at a low overpotential of 250 mV and a small Tafel slope of 106 mV decade −1 , which are better than those of related metal-free electrocatalysts. The high HER activity of TpPAM was investigated in-depth via theoretical density functional theory (DFT) calculations. The theoretical findings were correlated with the experimental results, and these were in good agreement for high HER catalytic efficiency of the porous TpPAM polymer. The Faradaic efficiency of the TpPAMbased electrode was found to be 98%, which is very close to the ideal value of 100%, reflecting its potential for practical implementation. Moreover, the as-synthesized catalyst showed good stability by retaining 91% of the initial current density after 1000 cycles.

Covalent organic frameworks (COFs) have attracted surging interest lately due to their wide potential in several frontline application areas like gas storage, sensing, photovoltaics, fuel cells, active catalyst supports, and so on. However, only very few reports are available for the metal-free electrocatalysis over COFs. Herein, we developed a new thiadiazole-based COF, C4-SHz COF, through the reaction between 1,3,5-tris(4-formylphenyl)benzene and 2,5-dihydrazinyl-1,3,4-thiadiazole that possesses a very high specific surface area of 1224 m 2 g −1 , unique molecular architecture, high porosity, and abundant active sites. The as-synthesized C4-SHz COF displayed superior electrocatalytic oxygen evolution reaction (OER) activity and excellent long-term durability. The electrocatalytic performance of the C4-SHz COF achieved a current density of 10 mA/cm 2 at an overpotential of 320 mV. The higher activity of the C4-SHz COF could be attributed to the high Brunauer−Emmett−Teller surface area, porosity, and network structure of the π-conjugated organic building blocks, which allowed fast charge and mass transport processes. This work validates the promising potential of a metal-free COF electrocatalyst toward the OER and its capability to replace carbon-based electrocatalysts.

Sustainable supply of energy is one of the biggest challenges today. The conversion of energy from any abundant and renewable resources would be an ideal solution for this ever increasing demand of sustainable energy. Biomass provides a potential energy alternative through the platform chemical 5‐hydroxymethylfurfural (HMF), which is considered as a sustainable source for liquid fuels and commodity chemicals. Herein, we report the synthesis of a nanoporous polytriphenylamine (PPTPA‐1) having high surface area (1437 m2 g−1) by a simple one‐step oxidative polymerization pathway. Upon sulfonation of PPTPA‐1, the sulfonated polymer SPPTPA‐1 showed very high surface acidity and it has been successfully employed as a solid acid catalyst for direct conversion of sugar to HMF. Both PPTPA‐1 and SPPTPA‐1 materials have distinct nanofiber morphologies and they are characterized thoroughly by using powder XRD, FTIR spectroscopy, 13C solid state magic‐angle‐spinning NMR spectrometry, field‐emission scanning electron microscopy, high‐resolution transmission electron microscopy, and N2 sorption techniques. We have optimized the HMF yields by using different carbohydrate sources and estimated the recycling efficiency of the catalyst.

Herein we have developed a highly active, robust, and selective porous organic polymer (PPTPA-1, POP) encapsulated magnetically retrievable Pd-Fe 3 O 4 nanohybrid catalyst in a one-step solvothermal route and investigated its catalytic performance in levulinic acid (LA) hydrogenation, a key platform molecule in many biorefinery schemes, to γ-valerolactone (GVL), employing formic acid as sustainable H 2 source. The specific textural and chemical characteristics of as-synthesized nanohybrid materials were identified by XRD, XPS, FT-IR, 13 C CP MAS NMR, HR-TEM, and FE-SEM with the corresponding elemental mapping and nitrogen physisorption studies. It was found that the nanohybrid Pd-Fe 3 O 4 /PPTPA-1 catalyst exhibited a substantially enhanced activity in comparison with the monometallic catalysts (Pd/PPTPA-1 and Fe 3 O 4 /PPTPA-1). Evidence of the electronic interaction between Pd and Fe attributable to the intrinsic hybrid synergistic effect is thought to be responsible for this superior catalytic performance and improvement in catalyst stability. The recycling experiments revealed that the magnetic nanohybrid catalyst sustained remarkable recycling efficiency and magnetism after being used in 10 successive catalytic runs, which made Pd-Fe 3 O 4 /PPTPA-1 a potential catalyst for the production of GVL in industry.

Hg/Hg(II) have been recognized as being highly poisonous to humans as they cause severe health and environmental problems. Designing a suitable adsorbent decorated with an abundance of accessible chelating sites at the solid surface together with high affinity for heavy metals is a big challenge to overcoming mercury contamination. Here we report a new thioether-functionalized covalent triazine nanosphere, SCTN-1, which has been employed as a highly efficient adsorbent for the removal of toxic mercury from contaminated water with an excellent adsorption performance of 1253 and 813 mg g −1 for Hg 2+ and Hg(0) respectively, which largely outperforms several recently reported thiol and thioether-functionalized adsorbents. Our kinetic studies suggest that SCTN-1 showed the fastest adsorption rate for the removal of mercury from aqueous solutions among all adsorbents known until date. Based on its adsorption performance and high recycling efficiency, this thio-functionalized nanoporous polymeric material has huge potential to be explored in environmental remediation.