Hydrogen-Bonded Organic Framework Structure: A Metal-Free Electrocatalyst for the Evolution of Hydrogen.

The hydrogen-bonded organic frameworks (HOFs) have gained significant attention due to their various alluring applications in the fascinating field of supramolecular chemistry. Herein, we report the electrocatalytic activity of HOFs toward the hydrogen evolution reaction (HER) by utilizing the molecular adduct of cyanuric and trithiocyanuric acid with various organic substrates (melamine and 4,4'-bipyridine). Both the experimental and theoretical findings provide insights and validate the electrocatalytic activity toward HER applications. This work contributes significantly to designing novel highly efficient metal-free HOF-based electrocatalysts for the HER.

Metal-Free Triazine-Based 2D Covalent Organic Framework for Efficient H2 Evolution by Electrochemical Water Splitting.

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 H2 SO4 . 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.

Single Atom on the 2D Matrix: An Emerging Electrocatalyst for Energy Applications.

The electrochemical energy conversions play an essential role in the production of sustainable and renewable energy. However, the performance is not up to the mark due to the absence of highly efficient and stable electrocatalysts. Recently, both 2D-matrix and single-atom catalysts (SACs) are two intense research topics in the field of electrocatalysis due to the high activity and stability and to maximize the utilization efficiency. Engineering the materials from 3D to 2D and modification from nanoparticles to single atoms have created a significant enhancement in the electrocatalytic activity. Hybridizing both the 2D matrix and SACs (2DM@SACs) creates a new electronic state in the materials, and that bequeaths with enhancing potentials toward the electrocatalytic activity. The strong covalent interaction between the 2D matrix and SACs tunes the intrinsic activity of the electrocatalysts. In this mini-review, we have discussed the different synthesis methods of 2DM@SACs with a focus on their electrochemical energy applications such as hydrogen evolution, oxygen evolution, oxygen reduction, and carbon dioxide reduction. This mini-review appraises the contribution to the rational proposal for the synthesis of perfect 2DM@SAC catalysts with their electrochemical properties toward energy conversion applications.

Ag nanoparticle-decorated, ordered mesoporous silica as an efficient electrocatalyst for alkaline water oxidation reaction.

In recent years, several novel strategies for speeding up the slow kinetics of the water oxidation reaction have attracted considerable attention for generation of O2. This is particularly important from the environmental perspective. Here we report a SBA-15 type, 2D-hexagonal functionalized mesoporous organosilica material as support for small Ag nanoparticles (NPs) by grafting the silica surface with 3-aminopropyltriethoxysilane, followed by chemical impregnation of Ag NPs at its surface, to obtain a AgNPs@SBA-NH2 material. The AgNPs@SBA-NH2 has been thoroughly characterized using several instrumental tools, such as powder X-ray diffraction, ultra-high resolution transition electron microscopy, N2 sorption, FT-IR spectroscopy, thermogravimetric and differential thermal analysis and X-ray photoelectron spectroscopy. High Brunauer-Emmett-Teller (BET) surface area and fine dispersion of Ag NPs throughout the surface of the amine-functionalized mesoporous material could enhance the rate of oxygen evolution reaction (OER) activity for AgNPs@SBA-NH2 in the electrochemical water splitting reaction.

Highly Active 2D Layered MoS 2 -rGO Hybrids for Energy Conversion and Storage Applications.

The development of efficient materials for the generation and storage of renewable energy is now an urgent task for future energy demand. In this report, molybdenum disulphide hollow sphere (MoS2-HS) and its reduced graphene oxide hybrid (rGO/MoS2-S) have been synthesized and explored for energy generation and storage applications. The surface morphology, crystallinity and elemental composition of the as-synthesized materials have been thoroughly analysed. Inspired by the fascinating morphology of the MoS2-HS and rGO/MoS2-S materials, the electrochemical performance towards hydrogen evolution and supercapacitor has been demonstrated. The rGO/MoS2-S shows enhanced gravimetric capacitance values (318 ± 14 Fg-1) with higher specific energy/power outputs (44.1 ± 2.1 Whkg-1 and 159.16 ± 7.0 Wkg-1) and better cyclic performances (82 ± 0.95% even after 5000 cycles). Further, a prototype of the supercapacitor in a coin cell configuration has been fabricated and demonstrated towards powering a LED. The unique balance of exposed edge site and electrical conductivity of rGO/MoS2-S shows remarkably superior HER performances with lower onset over potential (0.16 ± 0.05 V), lower Tafel slope (75 ± 4 mVdec-1), higher exchange current density (0.072 ± 0.023 mAcm-2) and higher TOF (1.47 ± 0.085 s-1) values. The dual performance of the rGO/MoS2-S substantiates the promising application for hydrogen generation and supercapacitor application of interest.