Hierarchical Nanoporous V2O3 Nanosheets Anchored with Alloy Nanoparticles for Efficient Electrocatalysis

Migration of vanadium oxide nanoparticles in saturated porous media

Vanadium oxides nanoparticles (VOx-NPs) as emerging functional materials are widely applied in high-technology industries. However, their environmental behaviors remain largely known. In this study, the migration of three common VOx-NPs (V2O5, VO2, and V2O3) in saturated porous media has been investigated. V2O5 NPs showed the highest migration ability under all conditions, compared to other VOx-NPs. Increasing ionic strength and decreasing pH hindered their migration, while the presence of Ca2 + was more effective than Na+ in depositing VOx-NPs. The combined results from multiple analyses (DLVO theory, MMS equations, Traj-Hap module of Parti-Suite and HYDRUS-1D simulation) suggested that high ionic strength and low pH reduced the energy barrier between the VOx-NPs and quartz sand, and increased the particulate sizes, making VOX-NPs more difficult to migrate. Changes in VOx-NPs size effected the contribution of gravity in retention fate. Small VOx-NPs (< 400 nm) delivered to both the upstream and downstream of the quartz sand surface, while large ones (> 900 nm) remained downstream. This study provides the insight into the geochemical fates of VOx-NPs, which is helpful to develop regulating strategies to reduce/eliminate their potential environmental risks.

Encapsulation of Cu-modified SnO2 yolk-shell in V2O5-amalgamated wrinkled g-C3N4 lamella for boosting antibiotic photodegradation

The remarkable application of tin oxide in various domains is indebted to its photoelectronic merits. However, significant efforts to discover its photocatalytic potential were restricted through arduous challenges, which were the amelioration of light-harvesting and -utilizing. In fact, the uncommon light absorption energy has drawn veil over the brilliance of astounding oxidation potential, which is much more than that of TiO2. Herein, our attention was focused on the taking advantages of self-template structure for simultaneously enjoying the two sides of photoelectronic justification as well as the S-step system for eminent charge dissociation. In this regard, the optimized Cu-modified SnO2 yolk-shell ((5)YS-CuSnO) spheres were engineered through the copper modulation into glycerate-assisted metal-organic structure. As a result, the exceptional light-harvesting was achieved through desirable defects and oxygen vacancy resulted from Cu-doping, and also efficient light-utilization was obtained by the multi-scattering/reflection effect resulted from multi-shell configuration. After the effectual incorporation (40 wt⁒) of (5)YS-CuSnO was encapsulated into the V2O5-decorated wrinkled g-C3N4 lamella (VO-WCN), the dual S-step VO-WCN@(5)YS-CuSnO introduced unprecedented levofloxacin (LFC) decontamination performance, which was kinetically 5.2 and 30.2-times greater than of the (5)YS-CuSnO and bare SnO2 yolk-shell. The conspicuous fulfillment of nanocomposite was manifested in the LFC mineralization, pharmaceutical effluent treatment within 360 min, and successive cycling reactions. The fusion of the extraordinary architecture of YS-CuSnO with S-Step system not only initiates the facile and practical photocatalytic exploitation, but shade light on some undeveloped side of tin oxide.

Tailoring competitive adsorption sites of hydroxide ion to enhance urea oxidation-assisted hydrogen production

Alloys with bimetallic electron modulation effect are promising catalysts for the electrooxidation of urea. However, the side reaction oxygen evolution reaction (OER) originating from the competitive adsorption of OH- and urea severely limited the urea oxidation reaction (UOR) activity on the alloy catalysts. This work successfully constructs the defect-rich NiCo alloy with lattice strain (PMo-NiCo/NF) by rapid pyrolysis and co-doping. By taking advantage of the compressive strain, the d-band center of NiCo is shifted downward, inhibiting OH- from adsorbing on the NiCo site and avoiding the detrimental OER. Meanwhile, the oxygenophilic P/Mo tailored specific adsorption sites to adsorb OH- preferentially, which further released the NiCo sites to ensure the enriched adsorption of urea, thus improving the UOR efficiency. As a result, PMo-NiCo/NF only requires 1.27 V and -57 mV to drive a current density of ±10 mA cm-2 for UOR and hydrogen evolution reaction (HER), respectively. With the guidance of this work, reactant competing adsorption sites could be tailored for effective electrocatalytic performance.

Fabrication of bimetallic-doped materials derived from a Cu-based complex for enhanced dye adsorption and iodine capture

In this work, we used Cu(II) ions, a bis-pyridyl-bis-amide ligand [N,N'-bis(4-pyridinecarboxamide)-1,2-cyclohexane (4-bpah)], and an aromatic dicarboxylic acid [1,4-cyclohexanedicarboxylic acid (H2CHDA)] to construct a 1D binuclear Cu-based complex, namely {[Cu3(4-bpah)(CHDA)3(H2O)]·2H2O}n (1). Moreover, we also developed a facile method to synthesize two monometallic/bimetallic-doped materials which were derived from the Cu complex (C-N-1 and C-V-1, which were doped with nitrogen and vanadium, respectively). The as-synthesized derived materials were fully characterized and the iodine sorption/release capabilities were investigated in detail. We performed iodine adsorption experiments on the two monometallic/bimetallic-doped materials and found that C-N-1 and C-V-1 possess highly efficient adsorption activities for the adsorption of iodine from solution. The C-N-1 and C-V-1 complexes exhibited remarkable adsorption capacities of 1141.60 and 1170.70 mg g-1, respectively, for iodine from a cyclohexane solution. Moreover, the dye adsorption properties of C-N-1 and C-V-1 were also investigated in detail. The obtained C-N-1 and C-V-1 exhibit effective dye uptake performances in water solution. The adsorption of Congo red (CR) on a single metal carbon material C-N-1 doped with heteroatoms reached equilibrium within 240 min and reached an adsorption capacity of 1357.00 mg g-1 and the adsorption capacities of C-V-1 for methylene blue (MB), gentian violet (GV), rhodamine B (RhB), and CR at room temperature were found to be 187.60, 190.60 and 108.10 and 1501.00 mg g-1 in 180 min, respectively. By comparison, we found that doping vanadium could play an important role in the adsorption processes. The adsorption capacity of C-V-1 (containing the vanadium in its structure) was relatively higher than that of C-N-1, which indicated that the introduction of non-noble metals may effectively tune the adsorption kinetics activity and the introduction of noble metals can change the surface electronegativity of porous carbon materials, thus leading to significantly improved adsorption capabilities.

Heterogeneous Fe-Doped Ni(OH)2 Grown on Nickel Mesh by Electrodeposition for Efficient Alkaline Oxygen Evolution Reaction

Designing highly excellent and stable catalysts for alkaline oxygen evolution reaction (OER) is gradually pivotal for clean energy development. In this work, a heterogeneous Fe-doped Ni(OH)2 (Ni/Fe-0.1) was developed via simple one-step electrodeposition onto nickel mesh. The heterogeneous interface structure generates sufficient active sites, significantly improving OER performance with an overpotential of 174 mV at 10 mA cm-2 (η10 ), while Tafel slope is only 43.0 mV dec-1 . In particular, Ni/Fe-0.1 is still able to operate stably at a current density of 1 A cm-2 for 100 h without obvious potential decay. The oxidation of Ni2+ to Ni3+ was detected by X-ray photoelectron spectroscopy, proving that the heterogeneous catalyst could stabilize the high-valence state of nickel as active sites to its superior OER performance. This work provides a convenient synthetic strategy for forming heterogeneous catalysts toward efficient water electrolysis.

Vanadium Oxide: Phase Diagrams, Structures, Synthesis, and Applications

Vanadium oxides with multioxidation states and various crystalline structures offer unique electrical, optical, optoelectronic and magnetic properties, which could be manipulated for various applications. For the past 30 years, significant efforts have been made to study the fundamental science and explore the potential for vanadium oxide materials in ion batteries, water splitting, smart windows, supercapacitors, sensors, and so on. This review focuses on the most recent progress in synthesis methods and applications of some thermodynamically stable and metastable vanadium oxides, including but not limited to V₂O₃, V₃O₅, VO₂, V₃O₇, V₂O₅, V₂O₂, V₆O₁₃, and V₄O₉. We begin with a tutorial on the phase diagram of the V-O system. The second part is a detailed review covering the crystal structure, the synthesis protocols, and the applications of each vanadium oxide, especially in batteries, catalysts, smart windows, and supercapacitors. We conclude with a brief perspective on how material and device improvements can address current deficiencies. This comprehensive review could accelerate the development of novel vanadium oxide structures in related applications.

Cobalt-Carbon nanotubes supported on V2O3 nanorods as sulfur hosts for High-performance Lithium-Sulfur batteries

Exploring advanced sulfur cathode materials with high catalytic activity to accelerate the slow redox reactions of lithium polysulfides (LiPSs) is of great significance for lithium-sulfur batteries (LSBs). In this study, a coral-like hybrid composed of cobalt nanoparticle-embedded N-doped carbon nanotubes supported by Vanadium (III) oxide (V₂O₃) nanorods (Co-CNTs/C @V₂O₃) was designed as an efficient sulfur host using a simple annealing process. Characterization combined with electrochemical analysis confirmed that the V₂O₃ nanorods exhibited enhanced LiPSs adsorption capacity, and the in situ grown short-length Co-CNTs improved electron/mass transport and enhanced the catalytic activity for conversion to LiPSs. Owing to these merits, the S@Co-CNTs/C@V₂O₃ cathode exhibits effective capacity and cycle lifetime. Its initial capacity was 864 mAh g^-1 at 1.0C and remained at 594 mAh g^-1 after 800cycles with a decay rate of 0.039%. Furthermore, even at a high sulfur loading (4.5 mg cm^-2), S@Co-CNTs/C@V₂O₃ also shows acceptable initial capacity of 880 mAh g^-1 at 0.5C. This study provides new ideas for preparing long-cycle S-hosting cathodes for LSBs.

In situ fabrication of HDA-mediated NiFe–Fe2O3 nanorods: an efficient and recyclable heterogeneous catalyst for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones in water

A simple, facile and an effective route for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones via multi-component reactions using newly developed NiFe–Fe2O3 nanorods as heterogeneous catalysts.

Electronic Interaction between In Situ Formed RuO2 Clusters and a Nanoporous Zn3V3O8 Support and Its Use in the Oxygen Evolution Reaction

The catalytic activity and durability of RuO₂ clusters toward the oxygen evolution reaction (OER) are strongly associated with their support; however, how the electronic interaction would enhance the catalytic performance is still not quite clear. Herein, hierarchical nanoporous and single-crystal Zn₃V₃O₈ nanosheets are adopted to anchor in situ formed RuO₂ clusters. X-ray photoelectron analysis reveals significant binding energy changes of both Ru and V due to the creation of strong Ru-O-V bonding interaction, which would lead to the reconstruction of the electronic structure of the Zn₃V₃O₈ matrix and RuO₂ clusters. The ultrastrong electronic interaction also results in superior OER activity, indicated by a small overpotential at 10 mA cm^-2 (228 mV) and a shallow Tafel slope of 46 mV dec^-1. First-principles simulation further reveals the synergistic effect derived from the unique RuO₂@Zn₃V₃O₈ couple, which effectively regulates the electronic structure for the OER process. In addition, the created interfacial chemical bond and the confined microporous structure of the Zn₃V₃O₈ substrate could prevent the RuO₂ clusters from detachment and aggregation, making the nanocomposite a promising long-term stable OER electrocatalyst.

Intrinsic activity modulation and structural design of NiFe alloy catalysts for an efficient oxygen evolution reaction

NiFe alloy catalysts have received increasing attention due to their low cost, easy availability, and excellent oxygen evolution reaction (OER) catalytic activity. Although it is considered that the co-existence of Ni and Fe is essential for the high catalytic activity, the identification of active sites and the mechanism of OER in NiFe alloy catalysts have been controversial for a long time. This review focuses on the catalytic centers of NiFe alloys and the related mechanism in the alkaline water oxidation process from the perspective of crystal structure/composition modulation and structural design. Briefly, amorphous structures, metastable phases, heteroatom doping and in situ formation of oxyhydroxides are encouraged to optimize the chemical configurations of active sites toward intrinsically boosted OER kinetics. Furthermore, the construction of dual-metal single atoms, specific nanostructures, carbon material supports and composite structures are introduced to increase the abundance of active sites and promote mass transportation. Finally, a perspective on the future development of NiFe alloy electrocatalysts is offered. The overall aim of this review is to shed light on the exploration of novel electrocatalysts in the field of energy.

Recent Progress on NiFe-Based Electrocatalysts for the Oxygen Evolution Reaction

The seriousness of the energy crisis and the environmental impact of global anthropogenic activities have led to an urgent need to develop efficient and green fuels. Hydrogen, as a promising alternative resource that is produced in an environmentally friendly and sustainable manner by a water splitting reaction, has attracted extensive attention in recent years. However, the large-scale application of water splitting devices is hindered predominantly by the sluggish oxygen evolution reaction (OER) at the anode. Therefore, the design and exploration of high-performing OER electrocatalysts is a critical objective. Considering their low prices, abundant reserves, and intrinsic activities, NiFe-based bimetal compounds are widely studied as excellent OER electrocatalysts. Moreover, recent progress on NiFe-based OER electrocatalysts in alkaline environments is comprehensively and systematically introduced through various catalyst families including NiFe-layered hydroxides, metal-organic frameworks, NiFe-based (oxy)hydroxides, NiFe-based oxides, NiFe alloys, and NiFe-based nonoxides. This review briefly introduces the advanced NiFe-based OER materials and their corresponding reaction mechanisms. Finally, the challenges inherent to and possible strategies for producing extraordinary NiFe-based electrocatalysts are discussed.