Copper-Based Ultrathin Nickel Nanocone Films with High-Efficiency Dropwise Condensation Heat Transfer Performance

We report a type of copper-based ultrathin nickel nanocone films with high-efficiency dropwise condensation heat transfer (DCHT) performance, which can be fabricated by facile electrodeposition and low-surface-energy chemistry modification. Compared with flat copper samples, our nanosamples show condensate microdrop self-propelling (CMDSP) function and over 89% enhancement in the DCHT coefficient. Such remarkable enhancement may be ascribed to the cooperation of surface nanostructure-induced CMDSP function as well as in situ integration and ultrathin nature of nanofilms. These findings are very significant to design and develop advanced DCHT materials and devices, which help improve the efficiency of thermal management and energy utilization

Self-assembled MoS₂‑GO Framework as an Efficient Cocatalyst of CuInZnS for Visible-Light Driven Hydrogen Evolution

A ternary heterostructured CuInZnS/MoS₂-GO (graphene oxide) photocatalyst was constructed by a simple two-step hydrothermal method. The three-dimensional hierarchical architecture of MoS₂-GO hydrogel was first synthesized through a facile hydrothermal method. The obtained MoS₂-GO hydrogel with ultralow density and high surface area was redispersed into water and composite with CuInZnS. The resulting catalysts were analyzed by systematic characterizations including X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Raman, and UV–vis diffuse reflectance spectra (DRS), et al. The noble metal-free composite exhibited dramatically enhanced photocatalytic performance toward hydrogen evolution. The enhanced solar water splitting performance could be ascribed to the synergetic effect of GO and MoS₂. GO served as an electron acceptor and transporter while MoS₂ provided abundant active sites for hydrogen evolution. We hope this work may give some perspectives on the construction of noble-metal free catalysts for visible-light driven hydrogen production

Clustered Ribbed-Nanoneedle Structured Copper Surfaces with High-Efficiency Dropwise Condensation Heat Transfer Performance

We report that the dropwise condensation heat transfer (DCHT) effectiveness of copper surfaces can be dramatically enhanced by in situ grown clustered ribbed-nanoneedles. Combined experiments and theoretical analyses reveal that, due to the microscopically rugged and low-adhesive nature of building blocks, the nanosamples can not only realize high-density nucleation but constrain growing condensates into suspended microdrops via the self-transport and/or self-expansion mode for subsequently self-propelled jumping, powered by coalescence-released excess surface energy. Consequently, our nanosample exhibits over 125% enhancement in DCHT coefficient. This work helps develop advanced heat-transfer materials and devices for efficient thermal management and energy utilization

Subcooled-Water Nonstickiness of Condensate Microdrop Self-Propelling Nanosurfaces

We report perfect humidity-tolerant subcooled-water nonstickiness on condensate microdrop self-propelling (CMDSP) surfaces. As exemplified by a CMDSP nanoneedle surface, we find that impinged subcooled drops can instantly rebound and simultaneously take away surface condensate. Remarkably, continuously poured subcooled water can also shed off on the nanosample surface. In sharp contrast, they instantly freeze on the contrast flat hydrophobic surface. Such a superior performance may be ascribed to nanostructure-induced extremely low solid–liquid interface adhesion and prevention of phase transition from the liquid subcooled water to the solid ice. These findings help in the development of low-adhesive superhydrophobic surfaces suitable for a cold and humid environment

Facile Fabrication of Anodic Alumina Rod-Capped Nanopore Films with Condensate Microdrop Self-Propelling Function

We report that aluminum surfaces can be endowed with condensate microdrop self-propelling (CMDSP) function by one-step voltage-rising mild anodization in hot phosphoric acid solution followed by fluorosilane modification. Via regulating reaction parameters, we can achieve anodic alumina self-standing rod-capped nanopore films and minimize their solid–liquid interface adhesion. Such low-adhesive nanostructured film owns remarkable CMDSP function, especially to condensate microdrops with sizes below 50 μm, differing from usual gravity-driven dropwise condensation on flat aluminum surfaces. Clearly, this work offers a facile, efficient, and industry-compatible approach to processing CMDSP aluminum materials, which is significant for developing innovative energy-saving air-conditioner heat exchangers

Prediction and Evaluation of Indirect Carbon Emission from Electrical Consumption in Multiple Full-Scale Wastewater Treatment Plants via Automated Machine Learning-Based Analysis

The indirect carbon emission from electrical consumption of wastewater treatment plants (WWTPs) accounts for large proportions of their total carbon emissions, which deserves intensive attention. This work proposed an automated machine learning (AutoML)-based indirect carbon emission analysis (ACIA) approach and predicted the specific indirect carbon emission from electrical consumption (SEe; kg CO2/m3) successfully in nine full-scale WWTPs (W1–W9) with different treatment configurations based on the historical operational data. The stacked ensemble models generated by the AutoML accurately predicted the SEe (mean absolute error = 0.02232–0.02352, R2 = 0.65107–0.67509). Then, the variable importance and Shapley additive explanations (SHAP) summary plots qualitatively revealed that the influent volume and the types of secondary and tertiary treatment processes were the most important variables associated with SEe prediction. The interpretation results of partial dependence and individual conditional expectation further verified quantitative relationships between input variables and SEe. Also, low energy efficiency with high indirect carbon emission of WWTPs was distinguished. Compared with traditional carbon emission analysis and prediction methods, the ACIA method could accurately evaluate and predict SEe of WWTPs with different treatment scales and processes with easily available variables and reveal qualitative and quantitative relationships inside datasets simultaneously, which is a powerful tool to benefit the “carbon neutrality” of WWTPs

Two-Dimensional MoS₂ Confined Co(OH)₂ Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes

The development of abundant and cheap electrocatalysts for the hydrogen evolution reaction (HER) has attracted increasing attention over recent years. However, to achieve low-cost HER electrocatalysis, especially in alkaline media, is still a big challenge due to the sluggish water dissociation kinetics as well as the poor long-term stability of catalysts. In this paper we report the design and synthesis of a two-dimensional (2D) MoS₂ confined Co­(OH)₂ nanoparticle electrocatalyst, which accelerates water dissociation and exhibits good durability in alkaline solutions, leading to significant improvement in HER performance. A two-step method was used to synthesize the electrocatalyst, starting with the lithium intercalation of exfoliated MoS₂ nanosheets followed by Co²⁺ exchange in alkaline media to form MoS₂ intercalated with Co­(OH)₂ nanoparticles (denoted Co-Ex-MoS₂), which was fully characterized by spectroscopic studies. Electrochemical tests indicated that the electrocatalyst exhibits superior HER activity and excellent stability, with an onset overpotential and Tafel slope as low as 15 mV and 53 mV dec^–1, respectively, which are among the best values reported so far for the Pt-free HER in alkaline media. Furthermore, density functional theory calculations show that the cojoint roles of Co­(OH)₂ nanoparticles and MoS₂ nanosheets result in the excellent activity of the Co-Ex-MoS₂ electrocatalyst, and the good stability is attributed to the confinement of the Co­(OH)₂ nanoparticles. This work provides an imporant strategy for designing HER electrocatalysts in alkaline solutions, and can, in principle, be expanded to other materials besides the Co­(OH)₂ and MoS₂ used here

Sensitive Determination of 3-Hydroxy-2-Butanone with Double-Layer Mesoporous Tin (IV) Oxide Nanotubes Prepared by Single-Nozzle Electrospinning

Yolk-shell SnO2 mesoporous double-layer nanotubes were synthesized in one-step by single nozzle electrospinning. Compared with the traditional electrospinning using polyvinylpyrrolidone (PVP) as the precursor polymer to obtain the single nanotube material, two PVPs (PVPK88-96 and PVPK23-27) with different molecular weights in solution coupled with Sn2+ easily form the core-shell structure nanofiber through phase separation. The yolk-shell double-layer SnO2 nanotubes were obtained after calcination at 600 °C for 2 h. The yolk-shell SnO2 mesoporous double-layer nanotube is a promising sensing material toward 3-hydroxy-2-butanone as it shows high sensitivity, cycling stability, and selectivity. Moreover, the response and recovery times of the yolk-shell SnO2 mesoporous double-layer nanotubes toward 1 ppm 3-hydroxy-2-butanone were 122 s and 117 s.</p

Mitigating Cation Diffusion Limitations and Intercalation-Induced Framework Transitions in a 1D Tunnel-Structured Polymorph of V₂O₅

The design of cathodes for intercalation batteries requires consideration of both atomistic and electronic structure to facilitate redox at specific transition metal sites along with the concomitant diffusion of cations and electrons. Cation intercalation often brings about energy dissipative phase transformations that give rise to substantial intercalation gradients as well as multiscale phase and strain inhomogeneities. The layered α-V₂O₅ phase is considered to be a classical intercalation host but is plagued by sluggish diffusion kinetics and a series of intercalation-induced phase transitions that require considerable lattice distortion. Here, we demonstrate that a 1D tunnel-structured ζ-phase polymorph of V₂O₅ provides a stark study in contrast and can reversibly accommodate Li-ions without a large distortion of the structural framework and with substantial mitigation of polaronic confinement. Entirely homogeneous lithiation is evidenced across multiple cathode particles (in contrast to α-V₂O₅ particles wherein lithiation-induced phase transformations induce phase segregation). Barriers to Li-ion as well as polaron diffusion are substantially diminished for metastable ζ-V₂O₅ in comparison to the thermodynamically stable α-V₂O₅ phase. The rigid tunnel framework, relatively small changes in coordination environment of intercalated Li-ions across the diffusion pathways defined by the 1D tunnels, and degeneracy of V 3d states at the bottom of the conduction band reduce electron localization that is a major impediment to charge transport in α-V₂O₅. The 1D ζ-phase thus facilitates a continuous lithiation pathway that is markedly different from the successive intercalation-induced phase transitions observed in α-V₂O₅. The results here illustrate the importance of electronic structure in mediating charge transport in oxide cathode materials and demonstrates that a metastable polymorph with higher energy bonding motifs that define frustrated coordination environments can serve as an attractive intercalation host

Mitigating Cation Diffusion Limitations and Intercalation-Induced Framework Transitions in a 1D Tunnel-Structured Polymorph of V₂O₅

The design of cathodes for intercalation batteries requires consideration of both atomistic and electronic structure to facilitate redox at specific transition metal sites along with the concomitant diffusion of cations and electrons. Cation intercalation often brings about energy dissipative phase transformations that give rise to substantial intercalation gradients as well as multiscale phase and strain inhomogeneities. The layered α-V₂O₅ phase is considered to be a classical intercalation host but is plagued by sluggish diffusion kinetics and a series of intercalation-induced phase transitions that require considerable lattice distortion. Here, we demonstrate that a 1D tunnel-structured ζ-phase polymorph of V₂O₅ provides a stark study in contrast and can reversibly accommodate Li-ions without a large distortion of the structural framework and with substantial mitigation of polaronic confinement. Entirely homogeneous lithiation is evidenced across multiple cathode particles (in contrast to α-V₂O₅ particles wherein lithiation-induced phase transformations induce phase segregation). Barriers to Li-ion as well as polaron diffusion are substantially diminished for metastable ζ-V₂O₅ in comparison to the thermodynamically stable α-V₂O₅ phase. The rigid tunnel framework, relatively small changes in coordination environment of intercalated Li-ions across the diffusion pathways defined by the 1D tunnels, and degeneracy of V 3d states at the bottom of the conduction band reduce electron localization that is a major impediment to charge transport in α-V₂O₅. The 1D ζ-phase thus facilitates a continuous lithiation pathway that is markedly different from the successive intercalation-induced phase transitions observed in α-V₂O₅. The results here illustrate the importance of electronic structure in mediating charge transport in oxide cathode materials and demonstrates that a metastable polymorph with higher energy bonding motifs that define frustrated coordination environments can serve as an attractive intercalation host