Band gap engineering of amine functionalized Ag(I)-based coordination polymers and their plasmonic Ag0 coupled novel visible light driven photo-redox system for selective oxidation of benzyl alcohol

We developed a one-pot synthetic route to design Ag nanoparticles (NPs) coupled mixed ligand Ag(I) coordination polymer (CP), Ag@Ag(I)-CP (40% NH2) for photocatalysis. Initial combined (experimental and DFT) study on mixed ligand CPs demonstrates that a rational substitution of ligand L1: 1,4-benzenedicarboxylate by L2: 2 amino 1,4-benzenedicarboxylate enhances porosity and reduction of energy gap (2.9 eV) due to highest occupied crystal orbital (HOCO; + 2.4 V vs. NHE) suitable for BA oxidation selectively to benzaldehyde (BD) ((E0 BA/BD = + 1.9 V). When Ag NP (~ 6–7 nm) is in-situ encapsulated on CP, formed a coupled structure Ag@Ag(I)-CP (40% NH 2), which offered advantages on BA oxidation (k (O2) = 7.4 × 10-4 min-1; yield: 19.1% BD, and k (persulfate) = 38.7 × 10-4 min-1; yield: 54.1% BD) along with significant stability, reusability and competitiveness than other Ag or precious metal NPs. The new material offers numerous possibilities for applications in oxidative organic transformations reactions. The simple synthetic strategy demonstrated in this work for the coupling of Ag(I) based coordination polymers with metal nanoparticles at the molecular scale for semiconductor like applications under visible light will accelerate extensive research in near future

Photoactive Ag(I)-based coordination polymer as a potential semiconductor for photocatalytic water splitting and environmental remediation: experimental and theoretical approach

Metal–organic frameworks or metal coordination polymers (CPs) with controlled structure on the micro/nanoscale have attracted intense interest for potential applications in a wide variety of fields, such as energy storage and conversion, chemical and biological sensing, and catalysis. Here, we report a new class of photocatalytic material, Ag(I)-based nano-micro-structured coordination polymer (Ag(I)-CP), which offers performance at a level competitive with known semiconductors in photocatalytic water oxidation and oxidation of organic compounds, such as dye/organic pollutants present in contaminated water. The coordination polymer was synthesized by a wet-chemical route and has been characterized using powder X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy. The Ag(I)-CP has notable semiconducting characteristics and charge transfer ability due to ligand-centered charge transfer in combination with metal-to-ligand charge transfer (Ag–O cluster to ligand center), as established from experimental absorption, luminescence, and photoelectrochemical measurements alongside density functional theory calculations. Notably, Ag(I)-CP exhibits a highly reactive valance band potential +3.40 V vs NHE, composed of hybridized state of O 2p and C 2p through the organic linker and Ag 4d; this acts as an active center for the generation of reactive oxygen species, i.e., hydroxyl radical and h+ under photocatalytic conditions. Consequently, the photogenerated species facilitate effective oxidations of water and organic contaminants such as tartrazine, rhodamine B, and 2,4-dichlorophenol under UV light irradiation. Furthermore, our results suggest that the Ag(I)-CP could be used as a promising material for the development of heterostructure for a variety of photoassisted redox catalysis reactions

Sustainable Design of Hierarchically Porous Ag₃PO₄ Microspheres through a Novel Natural Template and Their Superior Photooxidative Capacity

Uniform hierarchical Ag₃PO₄ porous microspheres were synthesized for the first time by a sustainable route based on a novel natural bone glue (BG)-assisted one-step precipitation reaction at room temperature. By varying experimental conditions such as the bone glue content, template constituents (amino acid, alginic acid), precursor concentration, temperature, pH, and reaction time, we could tune the morphology, porosity, size, and properties of Ag₃PO₄. All of the phases, microstructures with different architectures, and textural properties of the Ag₃PO₄ were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, and UV–vis diffuse reflectance spectroscopy. The oxidation state, local structure, and purity of the prepared Ag₃PO₄ were further characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, and thermogravimetric analysis. The influence of the template on the morphology was characterized by syntheses of Ag₃PO₄ using different templates such as glycine, alanine, and alginic acid, and products such as pyramidal-shaped Ag₃PO₄, Ag₃PO₄ dodecahedra, and coiled-rod-like porous Ag₃PO₄ were obtained, respectively. This revealed that self-assembly of the collagen protein present in the bone glue plays a significant role as a structure-directing agent, crystal growth modifier, and aggregation-orienting agent in the formation of unique Ag₃PO₄ porous microspheres. Detailed photocatalytic studies on aqueous rhodamine B and 2,4-dichlorophenol (2,4-DCP) in the presence of Ag₃PO₄ porous microspheres exhibited enhanced photocatalytic degradation under visible light that was significantly higher than for other architectures. The findings of this study should offer new insights into the development of porous hierarchical materials as high-performance visible-light photocatalysts and their potential utilization in environmental sustainability

Strategic Synthesis of SiO₂‑Modified Porous Co₃O₄ Nano-Octahedra Through the Nanocoordination Polymer Route for Enhanced and Selective Sensing of H₂ Gas over NO_<i>x</i>

In this work, a strategic synthesis of Co₃O₄ nano-octahedra was developed through the facile nanoscale coordination polymer (NCP) route, which was further modified by SiO₂ to be used as a sensor for enhanced sensing of hydrogen. The Co­(II)-NCP-derived Co₃O₄ octahedra and SiO₂-modified Co₃O₄ octahedra were characterized using Fourier transform infrared, powder X-ray diffraction, Brunauer–Emmett–Teller, thermogravimetric analysis, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction (H₂TPR) techniques. The SiO₂-modified Co₃O₄ sensor exhibited a stronger and selective electrical response to H₂ gas over NO_<i>x</i> at 225 °C than Co­(II)-NCP-derived Co₃O₄ octahedra and the conventional Co₃O₄ powder. The composite sensor shows faster recovery and significant repeatability than the other two. The enhancement in the sensing performance of the SiO₂-modified Co₃O₄ octahedron was explained by the effectiveness of surface modification, controlled morphology, and combination of synergistic effect of Co₃O₄ and SiO₂. Surface engineering of the as-prepared Co₃O₄ nano-octahedra with an exposed (111) surface plane and later SiO₂ modification facilitates effective gas adsorption, resulting in enhancement in sensing and selectivity over NO_<i>x</i>. The details of the synergistic effect and the plausible reasons for the improvement in gas-sensing parameters are discussed here. This study would offer new directions for development on the controlled synthesis of porous materials, in general, and in gas sorption or sensing, in particular