Decoration of Fe₃O₄ base material with Pd loaded CdS nanoparticle for superior photocatalytic efficiency

Decorated ternary Pd@CdS@Fe₃O₄ nanoarchitectures are synthesized by judicious loading of CdS nanoparticles without functionalizing the surface of the base materials, i.e., Fe₃O₄ and CdS. Here we have adopted a unique method to prepare Fe₃O₄ nanoparticles. In this ternary composite ferromagnetic Fe₃O₄ behaves as the catalyst carrier, CdS is used as semiconductor, and loaded Pd due to its high electron affinity behaves as a electron scavenger. CdS inherits visible light absorbing capability. Here Pd²⁺ is reduced to Pd upon deposition onto the CdS nanoparticles by the anionic S^2–. Then the ternary composite exhibits pronounced photocatalytic activity toward Rhodamine B oxidation under visible light irradiation in the yellow region. This composite happens to be much more efficient than that of pure CdS and CdS@Fe₃O₄ composite. Metallic Pd, due to its high electron withdrawing property, uptakes the electrons from the conduction band of CdS and increases the oxidative power of CdS. Because of the presence of Fe₃O₄ in the composite, the catalyst shows ferromagnetism, and thus after the photocatalytic experiments the catalyst is easily isolated from the reaction mixture. The efficiency of the photocatalyst decreases after five cycles because of the disintegration of the particle. The ternary composite serves as a convenient and efficient photocatalyst for degradation of dye molecules leading to the purification of water

Morphology Controlled Synthesis of SnS₂ Nanomaterial for Promoting Photocatalytic Reduction of Aqueous Cr(VI) under Visible Light

A mild, template free protocol has been demonstrated for SnS₂ nanoflake formation at the gram level from SnCl₂ and thioacetamide (TAA). The SnS₂ nanoflakes congregate to nanoflowers and nanoyarns with variable TAA concentrations. BET measurements reveal that the synthesized nanomaterials are highly porous having very high surface area, and the nanoflower has higher surface area than the nanoyarn. The synthesized nanomaterial finds application for promoting photoreduction of extremely toxic and lethal Cr­(VI) under visible light irradiation due to their porous nature. The nanoflowers photocatalyst is proved to be superior to nanoyarn due to the increased surface area and higher pore volume. It was also inferred that increased pH decreased the reaction rate. The present result suggests that the morphology-dependent photoreduction of Cr­(VI) by SnS₂ nanomaterial under visible light exposure will endorse a new technique for harvesting energy and purification of wastewater

Mesoporous Gold and Palladium Nanoleaves from Liquid–Liquid Interface: Enhanced Catalytic Activity of the Palladium Analogue toward Hydrazine-Assisted Room-Temperature 4‑Nitrophenol Reduction

The importance of an interfacial reaction to obtain mesoporous leafy nanostructures of gold and palladium has been reported. A new synthetic strategy involving 1,4-dihydropyridine ester (DHPE) as a potential reducing agent performs exceptionally well for the desired morphologies of both the noble metals at room temperature. The DHPE in turn transforms into its oxidized aromatic form. The as-synthesized gold leaves exhibit high surface-enhanced Raman scattering activity with rhodamine 6G (R6G) due to their hyperbranched structure. It is worthwhile that as-synthesized porous architectures of palladium support the room-temperature hydrogenation of 4-nitrophenol (4-NP) by hydrazine hydrate (N₂H₄·H₂O), reported for the first time. Furthermore, MPL exhibits exceptionally good catalytic activity toward electrooxidation of formic acid. Therefore, an aromaticity driven synthetic technique achieves a rationale to design leafy nanostructures of noble metals from the liquid–liquid interface for multifaceted applications

Crystal-Plane-Dependent Etching of Cuprous Oxide Nanoparticles of Varied Shapes and Their Application in Visible Light Photocatalysis

We report a simple, facile, surfactant-free chemical route to fabricate morphologically different Cu₂O nanoparticles such as octahedron, truncated octahedron, hollow octahedron, cube, and sphere by varying the hydrolyzing agents, complexing agent, and reducing agents. Then the componential and morphological evolution of Cu₂O nanoparticles have been studied independently, employing different etching agents such as aqueous NaOH, triethylamine (TEA), and oxalic acid solution. Particles of varied shapes and compositions resulted from the etching, and those particles were characterized by different physical methods. The oxidative dissolution of morphologically different Cu₂O nanoparticles with different etching agents depends on the exposed crystal planes. During oxidative dissolution in aqueous oxalic acid solution, it is realized that the stability of the (100) crystal plane is higher than that of the (111) crystal plane. Among all the etching reagents used, only oxalic acid exhibits shape transformation of the as-prepared Cu₂O nanoparticles. Oxalic acid etching causes the formation of cubes and hollow cubes as etching products with a 50% reduction of edge length compared to that of octahedral, truncated octahedral, and hollow octahedral Cu₂O nanoparticles. But ill-defined cubes are always obtained as the etching products with a 40% reduction of size compared to that of Cu₂O cubes and spheres. As-prepared Cu₂O nanoparticles and chemically etched products exhibit facet-dependent photocatalytic activity under visible light irradiation where mineralization of congo red takes place. Experimentally it has been concluded that photocatalytic activity of different particles bears a close relationship with exposed crystal planes, surface area, and particle size for congo red degradation. Interestingly, NaOH-etched product with hollow octahedral morphology bearing many (111) facets demonstrates the highest photocatalytic activity

Enhanced Catalytic Activity of Ag/Rh Bimetallic Nanomaterial: Evidence of an Ensemble Effect

A synergistic electronic interaction between the constituent metals in a bi/multimetallic system fine-tunes its catalytic property to be enhanced compared to those of the individual metal analogues. Such a proposition toward enhancing the catalytic activity of precious Rh metal by otherwise inactive Ag is done here in a cost-effective dilution method. The generated heterostructure of Ag/Rh independently drives two industrially important model reactions: 4-nitrophenol (4-NP) reduction and hydrogen peroxide (HP) decomposition. An impressive catalytic activity parameter for 4-NP reduction (256.67 s^–1 g^–1) with hydrazine and HP decomposition (39 × 10^–3 min^–1 g^–1) at room temperature ensures the importance of the “ensemble effect”. Spectroscopic evidence also certifies the dilution range to justify improved catalytic activities relating to the ensemble effect. Moreover, our theoretical study rationalizes the experimental observation where the enhanced charge transfer or occurrence of charge separation within the bimetallic system is responsible for the chemical reactivity of these bimetallic systems. Finally, the thermodynamics of formation of bimetallic nanoparticles finds support from the experimentally observed results and electronic interactions between Ag and Rh for improved catalytic activity that complies with spectral information

Decoration of Fe₃O₄ Base Material with Pd Loaded CdS Nanoparticle for Superior Photocatalytic Efficiency

Decorated ternary Pd@CdS@Fe₃O₄ nanoarchitectures are synthesized by judicious loading of CdS nanoparticles without functionalizing the surface of the base materials, i.e., Fe₃O₄ and CdS. Here we have adopted a unique method to prepare Fe₃O₄ nanoparticles. In this ternary composite ferromagnetic Fe₃O₄ behaves as the catalyst carrier, CdS is used as semiconductor, and loaded Pd due to its high electron affinity behaves as a electron scavenger. CdS inherits visible light absorbing capability. Here Pd²⁺ is reduced to Pd upon deposition onto the CdS nanoparticles by the anionic S^2–. Then the ternary composite exhibits pronounced photocatalytic activity toward Rhodamine B oxidation under visible light irradiation in the yellow region. This composite happens to be much more efficient than that of pure CdS and CdS@Fe₃O₄ composite. Metallic Pd, due to its high electron withdrawing property, uptakes the electrons from the conduction band of CdS and increases the oxidative power of CdS. Because of the presence of Fe₃O₄ in the composite, the catalyst shows ferromagnetism, and thus after the photocatalytic experiments the catalyst is easily isolated from the reaction mixture. The efficiency of the photocatalyst decreases after five cycles because of the disintegration of the particle. The ternary composite serves as a convenient and efficient photocatalyst for degradation of dye molecules leading to the purification of water

Serendipitous Synthesis of Ag_1.92Mo₃O₁₀·H₂O Nanowires from AgNO₃‑Assisted Etching of Ammonium Phosphomolybdate: A Material with High Adsorption Capacity

Ultralong Ag_1.92Mo₃O₁₀·H₂O nanowires have been serendipitously obtained due to selective etching of ammonium phosphomolybdate (APM) only by Ag⁺ ions in water under stirring conditions. The spherical yellow APM particle upon etching by Ag⁺ ions generates a hollow sphere, and PO₄^3– ions are expelled as a consequence of etching. The etching and hollowing disrupt the APM structure. Concentration of the etching agent and reaction time are crucial for the formation of Ag_1.92Mo₃O₁₀·H₂O nanowire. The growth of nanowires occurs probably due to etching followed by Ostwald ripening, oriented attachment, and splitting process. Finally, the as-synthesized nanowire exhibits a high capacity to adsorb cationic dyes on its surface. It shows superb adsorption properties, with maximum adsorption capacity of 110 mg g^–1, 175 mg g^–1, 160 mg g^–1 for Methylene Blue, Methyl Green, Crystal Violet, respectively. Moreover, the adsorption process of Methylene Blue on the nanomaterial was investigated taking it as a representative adsorbate. The selective adsorption capability of the nanomaterial toward cationic dye molecules makes it a competent candidate for water purification