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As a highly efficient and eco-friendly heat generation approach, the photothermal conversion process has been applied to many important areas such as desalination and medical treatments. We explored in this work the application of the photothermal conversion process for the fabrication of complex polymorphic calcium carbonate (CaCO3) structures. Through stepwise temperature modulation enabled by photothermal conversion, architectures of aragonite@calcite, calcite@aragonite, and calcite@aragonite@calcite that are composed of multiple polymorphic phases were obtained. The different polymorphic phases on the same architectures are confirmed by confocal Raman micro-spectroscopy analysis. Further modification of the substrates with a patterned self-assembled monolayer through soft lithography enabled the growth of arrays of the complex polymorphic CaCO3 structures on the surface. This study provides an efficient and promising methodology for thermally controlling the growth of materials with desired multi-phases and multi-functionalities for different applications. [ABSTRACT FROM AUTHOR]

A nitrogen-doped carbon-supported CuNi bimetallic nanocluster catalyst (CuNi–NC) was first synthesized via a facile ZIF-derived method. With a synergistic effect between Cu and Ni, the catalyst exhibited a maximum FECO of 96.3%. FECO is higher than 90% in a broad potential range of 600 mV, which was ascribed to the controllable pore size distribution. Density functional theory further demonstrated the preferred formation of *COOH in the catalytic process. [ABSTRACT FROM AUTHOR]

Films with nanoengineered surfaces have been extensively utilized in a variety of energy-related applications such as water desalination, thermal management and solar steam generation. To generate high-quality films, various generation methods including chemical vapor deposition (CVD), electrodeposition and microlithography have been studied. Compared to these methods, however, bubble-induced self-assembly (BISA) has been developed as an alternative strategy due to the advantages of being simple and cost-effective, and has generated considerable research efforts. In this paper, we review the recent advances in the development of films with nanoengineered surfaces via the BISA of nanomaterials. The mechanism and regulation of the BISA to generate high-performance films with the desired surface characteristics are discussed in detail. We also highlight the application of the BISA strategy for use in enhanced phase-change heat transfer. In addition, other applications of the BISA strategy are described, which range from effective thermal management of electronics and concentrated photovoltaics, to advanced energy storage and conversion. Finally, we discuss the current challenges and potential research directions in the field. It is expected that this review will provide a comprehensive understanding of the design, generation, applications and perspectives of films with nanoengineered surfaces generated by the BISA. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) have recently attracted significant attention due to their maximum atom utilization and high efficiency in a series of electrocatalytic reactions. However, the atomically dispersed metal atoms have intrinsically extreme mobility due to their high surface energy. Besides, the harsh reaction conditions of electrocatalysis also challenged the catalytic stability of SACs. The excellent electrocatalytic performance of SACs always degrades under long-term operating conditions. Most previous studies of SACs have focused more on the activity and selectivity of SACs in electrocatalysis, while catalytic stability has received little attention as a more critical factor limiting their large-scale industrial application. In this review, we provide an overview of the recent advances in SACs in terms of selecting the metal and support materials, synthetic strategies, and electrocatalytic applications with a focus on catalytic stability. A deep understanding of the instability behaviors of SACs under different electrocatalytic conditions contributes to the design of effective synthetic strategies to further optimize their catalytic stability, which is particularly discussed. Finally, we present the challenges and prospects for the future development of stable SACs in electrocatalysis. [ABSTRACT FROM AUTHOR]

We demonstrate a rapid one-step scalable microwave heating-based method to prepare Ti3C2Tx MXenes, which shortens the synthesis time from tens of hours for state-of-the-art approaches to 15 minutes and avoids time-consuming delamination with organic compounds. Noticeably, the microwave-synthesized MXene nanosheets have a tailorable size, a stable colloidal dispersion, high electrical conductivity and superior near-infrared (NIR) photothermal conversion performance. [ABSTRACT FROM AUTHOR]

Converting solar energy into storable thermal energy within organic phase change materials has emerged as a promising way to overcome solar intermittency and continuously harness solar-thermal energy for many heating-related applications. The low thermal conductivity and leakage issue of the phase change materials, however, limit scalable solar-thermal energy storage and their practical applications. Inspired by the dynamic thermoregulation behavior of butterfly wings, here we demonstrate rapid roll-to-roll solar-thermal energy harvesting within flexible form-stable composite phase change materials. Instead of static charging the bulk materials, the thin composite sheets are exposed to solar radiation for rapid charging while being continuously rolled. Due to shortened heat-diffusion distance and rollability of the composites, it achieves fast uniform solar-thermal energy storage within the bulk storage media. The flexibility of charged composites also enables broad tuning of the discharging behavior, and offers the possibility to explore wearable thermotherapy and other flexible solar-thermal applications. [ABSTRACT FROM AUTHOR]

The interaction between water and graphene oxide (GO), including water adsorption and desorption, has been widely used to demonstrate moisture-electric energy transformation (MEET). By taking advantage of water desorption stimulated by infrared (IR) light from a graphene oxide film with a gradient of oxygen-containing groups (O-group), a self-powered IR detection approach that can convert IR light into electric signals is demonstrated. The temperature sensitivity reaches 4.2 mK. With further optimization of the materials and structures, the performance of such self-powered IR detection can be further improved. The mechanism of the detection involving an IR/thermal effect on the interaction between vapor molecules and solid materials also has potential applications in thermal detection, thermal energy conversion, and chemical sensing. [ABSTRACT FROM AUTHOR]

This work explores an alternative approach to generate electric energy from a solar-driven interfacial water evaporation system. A thermo-electrochemical redox couple was combined with an evaporation system to take advantage of the temperature difference between the air–liquid interface and the bulk solution of water. An open thermo-electrochemical cell (TEC) was demonstrated to achieve the parallel processes of clean water generation and also electricity generation. Both deionized (DI) water and seawater (from the East China Sea) were used for the preparation of the electrolyte of the TEC system. Under one-sun illumination, the peak output electric power of the TEC with the seawater-based electrolyte was ∼0.5 mW m−2. The electric output of the TEC with the solution of seawater still reached ∼2.3 × 10−2 mW m−2 even without solar illumination due to the temperature difference generated by natural evaporation, which provides a possibility for electricity generation at night. The TECs can also be connected in series to increase the output voltage to charge capacitors or power LEDs, as demonstrated in the work. [ABSTRACT FROM AUTHOR]

Elemental composition, dimensionality and morphology are the main factors that influence the catalytic activity and stability of platinum-based and noble metal alloy nanocatalysts. Herein, we present a facile and cost-efficient approach to synthesize ternary alloy Pt–Pd–Ag nanoflowers by co-reduction of the metal precursors in aqueous solutions in a suitable molar ratio, involving hexamethylenetetramine as a structure-directing agent and ascorbic acid as a reducing agent. Both the presence of the aforementioned agents and the interaction between the component metals allow good control over the anisotropic growth of the ternary alloy nanostructure. The as-prepared nanocomposite demonstrates superior electrocatalytic activity towards the oxygen reduction reaction in acidic medium, compared with commercial Pt/C (20 wt%) and Pd/C (10 wt%) catalysts, as well as sufficiently good stability, as demonstrated by the accelerated durability test. The electrocatalytic activity of irregularly shaped nanoparticles of the same elemental composition was also measured, which revealed that the nanoflowers were superior catalysts owing to their specific morphological characteristics. Moreover, the nanoflowers displayed a relatively low electrochemical surface area decay (from 100% to 80.82%) due to their three-dimensional open-framework surface which can limit the aggregation of individual particles. [ABSTRACT FROM AUTHOR]

Solar-driven water evaporation has emerged as a highly efficient solar-thermal process to harness abundant clean solar energy for a variety of important applications. Herein, we rationally designed and developed a high-efficiency and fast-response solar-driven interfacial evaporation system by integrating a paper-based reduced graphene oxide (PrGO) composite membrane on top of a silicone-based porous insulation layer (PIL). The PrGO membrane that was prepared by using a cost-effective, scalable, simple fabrication process could effectively absorb and convert broadband solar light into heat to drive the evaporation process. Simultaneously, the hydrophilic PrGO membrane could provide continuous water supply through its strong capillary wicking effect. The floating PIL not only physically suspends the PrGO membrane but also thermally localizes solar heating at the air–water interface by suppressing downward heat conduction loss. Under one-sun illumination for 30 min, the resultant PrGO-PIL solar-driven interfacial evaporation system achieved steady-state and time-averaged evaporation efficiency of 89.7% and 80.6%, respectively. Theoretical analysis indicates that advantageous thermophysical properties of the evaporating materials together with rational design of the evaporation structure contribute to the superior evaporation performance. Such a high-efficiency solar-driven interfacial evaporation system has enabled consistent high-performance solar desalination of seawater under ambient one-sun illumination. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have attracted wide attention in photonic, electric, catalysis, and energy fields. Compared to the gas phase synthesis, the liquid phase route enables mass production of 2D materials with relatively low costs. However, these free-standing 2D materials obtained via the wet chemical route have a strong tendency to stack on each other; moreover, their 2D structure and the relevant functions degrade over time. Thus, we developed a strategy to achieve the reversibility of assembly/disassembly in Pd nanosheets (NSs) by utilizing anionic/cationic surfactants. Based on this methodology, the 2D structure of free-standing Pd NSs can be preserved with excellent performances for long-term use. Our results showed that free-standing Pd NSs were extremely unstable and decomposed into nanoparticles in 9 days. However, the assembled Pd NSs stacks maintained their 2D structure and preserved the methanol oxidation reaction (MOR) properties after disassembling. [ABSTRACT FROM AUTHOR]

Poor dispersion stability has become one of the major obstacles to the practical application of thermal nanofluids, especially for silicone-oil-based nanofluids that are used at relatively high operating temperatures. Herein, by using Fe3O4 nanofluid as a model system, we report a facile and effective strategy to prepare stably dispersed silicone-oil-based nanofluids that enable high-temperature operation. The strategy involves a series of processes, including controlled high-temperature synthesis of nanoparticles, surface modification of particles, and post-modification particle size partition. The solvothermally synthesized particles not only possess high thermal stability, but also allow for easy surface modification through ligand exchange. Phosphate-terminated polydimethylsiloxane ligands, which simultaneously possess high compatibility with silicone-oil-based fluid and high temperature stability, were used to exchange synthetic ligands and robustly anchor onto the particle surfaces, offering effective screening of the interparticle attraction. After centrifugal removal of the large-sized surface-modified particles, the prepared nanofluids have demonstrated stable dispersion at temperatures slightly lower than the particle synthesis temperature. The stably dispersed Fe3O4/silicone-oil nanofluids have been successfully utilized for consistent volumetric harvesting of solar thermal energy at more than 110 °C. [ABSTRACT FROM AUTHOR]

A nitrogen-doped carbon-supported CuNi bimetallic nanocluster catalyst (CuNi-NC) was first synthesized via a facile ZIF-derived method. With a synergistic effect between Cu and Ni, the catalyst exhibited a maximum FE CO of 96.3%. FE CO is higher than 90% in a broad potential range of 600 mV, which was ascribed to the controllable pore size distribution. Density functional theory further demonstrated the preferred formation of *COOH in the catalytic process.

Polymer-based thermal interface materials (TIMs) have attracted wide attention in the field of thermal management because of their outstanding properties including light weight, low cost, corrosion resistance and easy processing. However, the low thermal conductivity (∼0.2 W m -1 K -1 ) of the intrinsic polymer matrix largely degrades the overall thermal performance of polymer-based TIMs even those containing highly thermal conductive fillers. Hence, enhancing the intrinsic thermal conductivity of the polymer matrix is one of the most critical problems needed to be solved. This paper studies the thermal conductivity of poly(3,4-ethylenedioxythiophene) (PEDOT) films fabricated via cyclic voltammetry. By controlling the number of cycles in the electrochemical synthesis, different thickness of PEDOT films could be obtained. A time-domain thermoreflectance (TDTR) system was employed to evaluate the thermal performance of such as-prepared PEDOT films. We have demonstrated that a PEDOT film with thickness of 40 nm achieves the highest out-of-plane thermal conductivity of ∼0.60 W m -1 K -1 , which is almost three folds the thermal conductivity of commercially available pristine PEDOT:PSS film with similar thickness. The X-ray diffraction spectrum reveals that the PEDOT thin film with high crystallinity at the initial stage of electrochemical synthesis leads to enhanced thermal transportation. The findings in this work not only offer an opportunity to fabricate polymer materials exhibiting enhanced thermal conductivity, but also allow one to adjust the thermal performance of conducting polymers in practical applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We demonstrate a rapid one-step scalable microwave heating-based method to prepare Ti 3 C 2 T x MXenes, which shortens the synthesis time from tens of hours for state-of-the-art approaches to 15 minutes and avoids time-consuming delamination with organic compounds. Noticeably, the microwave-synthesized MXene nanosheets have a tailorable size, a stable colloidal dispersion, high electrical conductivity and superior near-infrared (NIR) photothermal conversion performance.

This paper introduces an approach to synthesize bimetallic nanoparticles under an alternating temperature field in aqueous solution. During the synthesis, pyro-catalytic barium titanate is used as the substrate to reduce the metallic ions dispersed in the solution due to the generated charges at the surface of pyro-materials under temperature oscillation. Chloroauric acid and potassium tetrachloroplatinate are used as precursors to produce gold/platinum bimetallic nanoparticles through a pyro-catalytic process. Transmission electron microscopy characterization, in combination with energy dispersive X-ray spectroscopy mapping, demonstrates that the bimetallic nanoparticle is composed of an Au core and Au/Pt alloy shell structure. Compared to the conventional approaches, the pyroelectric synthesis approach demonstrated in this work requires no toxic reducing agents and waste heat can be used as a thermal energy source in the synthesis. Hence, it offers a potential "green" synthetic method for bimetallic nanoparticles., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We have demonstrated Ag 3 PO 4 as an active non-Pt electrocatalyst with enhanced activity compared with Ag for oxygen reduction reaction (ORR). Density functional theory reveals that better ORR performance of Ag atoms on Ag 3 PO 4 surface than that on pure silver surface originates from more appropriate oxygen adsorption on positively charged Ag atoms. Further study of the surface geometry of Ag 3 PO 4 including tetrahedron, rhombic dodecahedron and cube indicates that the highest density of Ag and appropriate oxygen adsorption on {110} surface of rhombic dodecahedral Ag 3 PO 4 lead to the highest ORR activity, which is about 12 times that of Pt catalysts from a commercial perspective. It may be applicable for developing low-cost and highly active non-Pt catalytic materials from a broader range of material systems., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)