Rare Metals最新文献

The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure, especially under high current densities. Herein, a newly designed lamella-heterostructured nanoporous CoFe/CoFe₂O₄ and CeO_2−x, in situ grown on nickel foam (NF), holds great promise as a high-efficient bifunctional electrocatalyst (named R-CoFe/Ce/NF) for water splitting. Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization. By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_2−x heterostructure interfaces, the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution (η₁₀ = 227 mV; η₅₀₀ = 450 mV) and hydrogen evolution (η₁₀ = 35 mV; η₄₀₈ = 560 mV) reactions with high normalized electrochemical active surface areas, respectively. Additionally, the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm⁻² only at 1.75 V; the decline of activity is satisfactory after 100-h durability test at 300 mA·cm⁻². Density functional theory also demonstrates that the electron can transfer from CeO_2−x by virtue of O atom to CoFeOOH at CoFeOOH/CeO_2−x heterointerfaces and enhancing the adsorption of reactant, thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting.

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Photocatalytic conversion of CO₂ is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development. Nowadays, polymeric carbon nitride (PCN) has gained widespread application in CO₂ solar reduction due to its excellent visible light response, suitable conduction band position, and good cost-effectiveness. However, the amorphous nature and low conductivity of PCN limit its photocatalytic efficiency by leading to low carrier concentrations and facile electron–hole recombination during photocatalysis. Addressing this bottleneck, in this study, potassium-doped PCN (KPCN)/copper(II)-complexed bipyridine hydroxyquinoline carboxylic acid (Cu(II)(bpy)(H₂hqc)) composite catalysts were synthesized through a multistep microwave heating process. In the composite, the formation of an S-scheme junction facilitates the enrichment of more negative electrons on the conduction band of KPCN via intermolecular electron–hole recombination between Cu(II)(bpy)(H₂hqc) (CuPyQc) and KPCN, thereby promoting efficient photoreduction of CO₂ to CO. Microwave heating enhances the amidation reaction between these two components, achieving the immobilization of homogeneous molecular catalysts and forming amidation chemical bonds that serve as key channels for the S-scheme charge transfer. This work not only presents a new PCN-based catalytic system for CO₂ reduction applications, but also offers a novel microwave-practical approach for immobilizing homogeneous catalysts.

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In this study, cobalt-incorporated polydopamine coating onto Mn-modified mesoporous silica and successive graphitization treatment make the resulting composite afford abundant porosity, multiple metal active species, polar N sites, and excellent light-to-heat conversion ability. The controlled graphitization temperature was optimized to improve the activity state of metal species. The results reveal that Co₃O₄ nanoparticles incorporated thin-layer carbon formed onto the Mn-confined mesoporous silica, and more Co(II) and Mn(III) were generated in the MS-Co-500N₂ compared to MS-Co-500Air, which could cause the accelerated reaction cycles in the potassium peroxymonosulfate complex salt (PMS) activation. The degradation experiments demonstrated that the catalyst almost completely degraded biphenol A within 10 min with the reaction rate constant of 0.56 min⁻¹, nearly 205 times enhancement compared to the MS-Co-500Air. The free radicals trapping and quenching control demonstrated the dominant role of ¹O₂ and ·O₂ in the degradation process. Due to the efficient incorporation of Co₃O₄ nanoparticles and thin-layer carbon, the photothermal conversion properties were explored and utilized for solar-driving interface water evaporation and cleanwater recovery. To explore the practical application possibility in treating complicated polluted wastewater, the MS-Co-500N₂ materials were fixed on the melamine sponge by Ca ions-trigger alginate crosslinking strategy, and the integrated monolith evaporator shows an excellent water evaporation performance (1.52 kg·m⁻²·h⁻¹) and synchronous pollutant removal in biphenol A (94%, 10 min), carbamazepine (92%, 10 min), oxytetracycline (84%, 20 min) and norfloxacin (84%, 20 min).

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Metal clusters or even single-atoms dispersed and anchored on the photocatalysts’ surface can enhance photocatalytic performances on organic pollutant oxidation. Here, a simple photoreduction method was used to create atomically dispersed metal single-atoms/clusters (MSCs, M = Cu, Pd, Au and Ag) on P-modulated tubular carbon nitride (TCN). The obtained MSCs@TCN demonstrated excellent photocatalytic performances for the degradation of sulfamethazine (SMZ). In particular, the photocatalyst with 2 wt% Cu loading showed ultrahigh SMZ oxidation efficiency (k = 0.06110 min⁻¹), almost three times that of TCN (k = 0.02066 min⁻¹). It also shows excellent stability in the 5th-cycle measurements. The improved photocatalytic activity of the CuSCs@TCN is ascribed to the synergistic promotion of photogenerated charge separation by Cu single-atoms/clusters as active sites, accelerated charge transfer from bulk TCN to Cu sites through Cu–N_x interaction. Meanwhile, the active sites of Cu single-atoms/clusters could promote the production of ·O₂⁻, which participates in organic oxidation with strong oxidizing holes (h⁺). This strategy paves a new avenue for designing high-performance photocatalysts decorated with metal single-atoms and clusters.

Realizing the high thermoelectric performance of p-type AgBiSe₂-based materials has been challenging due to their low p-type dopability. This work demonstrated that Cd doping at the Bi site converts n-type AgBiSe₂ to p-type. The hole concentration is effectively increased with increasing Cd doping content, thereby enhancing the electrical conductivity. Theoretical calculations reveal that Cd doping flattens the edge of the valence band, resulting in an increase in the density-of-states effective mass and Seebeck coefficient. A record-high power factor of ~ 6.2 µW⋅cm⁻¹⋅K⁻² was achieved at room temperature. Furthermore, the induced dislocations enhance the phonon scattering, contributing to the ultralow lattice thermal conductivity across the entire temperature range. As a result, a decent figure of merit (zT) of ~ 0.3 at room temperature and a peak zT of ~ 0.5 at 443 K were obtained in AgBi_0.92Cd_0.08Se₂. Our work provides a feasible method for optimizing the thermoelectric performance of p-type AgBiSe₂.

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In the context of the global pursuit of sustainable energy, dual-atom catalysts (DACs) have attracted widespread attention due to their unique structural and excellent catalytic performance. Unlike the single-atom catalysts, DACs possess two active metal centers, exhibiting intriguing synergistic effects that significantly enhance their efficiency in various electrochemical reactions. This comprehensive review provides an overview of the recent advances in the field of dual-atom catalysts, focusing on their innovative preparation methods and strategies. It further delves into the intrinsic connections between structure and performance, discussing the applications of DACs in hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, photocatalysis, carbon dioxide reduction reaction, and batteries. Lastly, a forward-looking perspective addresses the current challenges and outlines future directions. This review aims to deepen our understanding of DACs and stimulate further innovation in advanced catalysts for energy conversion systems.

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Crystallization, while a common process in nature, remains one of the most mysterious phenomena. Understanding its physical mechanisms is essential for obtaining high-quality crystals. Typically, crystals grown by thermal evaporation or sublimation nucleate the substrate facing the evaporation source. Here, a novel vapor micro-turbulence mass transport mechanism in the growth process of ultrathin BiOCl single crystals has been revealed. In this mechanism, the precursor vapor bypasses the solid substrate, forming micro-turbulent vaporizing flows to nucleate on the surface of the substrate facing away from the evaporation source. Considering nucleation kinetics, fast shear flows are known to cause secondary nucleation, increasing nucleation quantity while decreasing the final size of the crystals. Thus, the nucleation and growth process of BiOCl crystals are controlled by adjusting the micro-turbulence intensity to reduce shear flow energy and dilate phase distribution, resulting in BiOCl crystals with uniform distribution and regular shape. Subsequent structural and morphological characterization confirms the high crystallization quality of the obtained crystals, and the performance of the constructed solar-blind photodetectors is comparable to that of similar devices. These findings contribute to a deeper understanding of vapor mass transport and crystal growth techniques and may be useful for applications related to metal oxide crystals.

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Developing efficient and stable electrocatalysts has always been the focus of electrochemical research. Here, sea urchin-like nickel-molybdenum bimetallic phosphide nickel-molybdenum alloy (Ni₄Mo) and (Ni-Mo-P) were successfully synthesized by hydrothermal, annealing and phosphating methods on nickel foam (NF). The unusual shape of the sea urchin facilitates gas release and mass transfer and increases the interaction between catalysts and electrolytes. The Ni₄Mo/NF and Ni-Mo-P/NF electrodes only need overpotentials of 72 and 197 mV to reach 50 mA·cm⁻² under alkaline conditions for hydrogen evolution reaction and oxygen evolution reaction, respectively. The Ni₄Mo/NF and Ni-Mo-P/NF asymmetric electrodes were used as anode and cathode for the overall water splitting, respectively. In 1.0 M KOH, at a voltage of 1.485 V, the electrolytic device generated 50 mA·cm⁻² current density, maintaining for 24 h without reduction. The labor presents a simple method to synthesize a highly active, low-cost, and strongly durable self-supporting electrode for over-water splitting.

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The acceleration of global industrialization and overuse of fossil fuels have caused the release of greenhouse gases and the disruption of the natural nitrogen cycle, leading to numerous energy and environmental problems. In response to the worsening situation, currently, achieving carbon neutrality and the nitrogen cycle is the most urgent task. In this case, reforming modern industrial production is of high importance and a great challenge as well. N-integrated carbon dioxide (CO₂) co-reduction has gained a lot of attention from the scientific community, particularly in recent years, and is considered a promising approach to turn waste into wealth and achieve carbon neutrality and a nitrogen cycle. In this review, a comprehensive review of the catalytic coupling of CO₂ and nitrogenous small molecules (such as N₂, NH₃ and NO_x) for the green synthesis of high-value chemicals is presented, including representative urea, amines, and amides. In these advances, in-depth discussions of C−N coupling are critically evaluated from the standpoints of catalyst design strategies and possible reaction mechanisms, highlighting the key factors and descriptors that affect the catalytic performance. Finally, the remaining challenges and further prospects are also proposed, with the aim of setting the trajectory for future development of green synthesis of high-value-added chemicals.

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