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Solar-driven interfacial evaporation has shown great promise for desalination due to its high photothermal conversion efficiency. However, for interfacial evaporation, the evaporator must have superior mechanical quality and strong thermal stability. To this end, ceramic nanofibrous mats with good mechanical strength can serve as a stable substrate for desalination. Herein, with the aid of finite element analysis, flexible Al2O3/TiO2 nanofibrous mats with robust mechanical properties are fabricated, where the stress dispersion greatly facilitates the Al2O3/TiO2 nanospheres to be uniformly dispersed into the mat. The flexible nanofibrous mats exhibit a high tensile strength up to 2.18 MPa. Afterward, a two-dimensional (2D) Al2O3/TiO2/MXene mat is constructed by a simple drop-casting method. Interestingly, the evaporation rate of the Al2O3/TiO2/MXene-2 mat reached 1.43 kg m−2 h−1, and the light-to-vapor energy conversion efficiency can reach 102% at a power density of 1.0 kW m−2. To measure the desalination efficiency, five ion concentrations in the collected water were found to be well below the safe salinity levels defined by standards set by the World Health Organization and U.S Environmental Protection Agency. Utilizing basic origami technology, the three-dimensional (3D) photothermal evaporator was integrated with the 2D mat due to its flexibility and ductility. Additionally, the evaporation rate increased to 1.61 kg m−2 h−1. This study is critical in the design of composite ceramic nanofiber materials with high flexibility and photothermal conversion efficiency for multifunctional desalination. [ABSTRACT FROM AUTHOR]

Solar-driven evaporation is highly promising for sustainable freshwater production without high energy-consumption. Till now, it has still been challenging to achieve both high performance and cost-effectiveness within one evaporator. In addition, the rarely reported strategy overcomes the obstacles of emerging microplastic-pollution in water sources and poor all-day-round evaporation. Herein, a low-cost, high-efficiency, biomass-derived three-dimensional (3D) graphene/cotton sponge with gradient vertical microchannels was readily constructed by simply stretching cotton. It served as a versatile photothermal platform with a high evaporation rate (2.49 kg m−2 h−1, normalized to both the top and side surfaces) and could withstand a large external stress of up to 8750-times its weight. Moreover, in the first attempt to efficiently evaporate water (90.6%) from a microplastic-polluted source, nearly 100% of the polyethylene (PE) microfibers were removed from evaporated water by 3D MoS2/graphene/cotton via reactive oxygen species attack and multi-level interception. New in situ FTIR microscopy technology was employed to accurately monitor the degradation mechanism of the PE microplastics. The PE degradation efficiency was as high as 19% in oxygen-enriched water, predominantly contributed by reactive O2˙−, and could be easily enhanced to 32% with the aid of additional reactive species (e.g., ˙HOO and H2O2) in 1 h. Besides, under the guidance of finite element analysis (FEA), a phase-change polyethylene glycol (PEG) layer was functionalized outside the graphene/cotton. Notably, it possessed a remarkably high all-day-round evaporation rate (1.63 kg per m2 per h per day, 1.42-times that achieved by a traditional evaporator without phase-change function) by utilizing thermal energy in the dark. This work gives promising alternative strategies for low-cost clean-water harvesting from microplastic-pollution and sustainable evaporation even under dark conditions. [ABSTRACT FROM AUTHOR]

As solar energy is readily available in most climates, solar evaporation plays a critical role in freshwater production and can be further integrated into various important applications. Demonstrated here is a plasmonic-antenna-coupled aerogel with confined heat at the micro and nanoscale levels based on vertically aligned Au/N-doped reduced graphene oxide (N-RGO) meshes towards an effective solar evaporation. The gradient microchannels in the aerogel were ably constructed by introducing gradient anti-freeze (i.e., NH4OH) concentrations in the hydrogel before freeze-drying to concentrate water to a central region (i.e., the hot zone). As plasmonic nanoantennas, Au nanoparticles were integrated on N-RGO meshes in/around nanopores to enhance energy harvesting and accurately localize heat for promoted in situ evaporation. Featuring broadband absorption (99.7%) and plasmon-enhanced photothermal conversion, this aerogel exhibits superior solar-to-vapor conversion (97.1%) and a high evaporation rate (2.72 kg m−2 h−1, normalized to both top and side surfaces), along with salt-resistance. Besides, the aerogel has been demonstrated as a novel solar-driven, anti-gravity catalytic reactor toward high value-added chemical (e.g., 4-aminophenol) conversions with high efficiency by localizing heat on reaction sites. This work provides an attractive strategy for the elegant manipulation of water and energy at multi-levels in solar evaporation and shows a novel approach to anti-gravity catalytic conversions driven by sunlight. [ABSTRACT FROM AUTHOR]

Catalyst sintering, a main cause of the loss of catalytic activity and/or selectivity at high reaction temperatures, is a major concern and grand challenge in the general area of heterogeneous catalysis. Although all heterogeneous catalysts are inevitably subjected to sintering during their operation, the immediate and drastic consequences can be mitigated by carefully engineering the catalytic particles and their interactions with the supports. In this tutorial review, we highlight recent progress in understanding the physical chemistry and materials science involved in sintering, including the discussion of advanced techniques, such as in situ microscopy and spectroscopy, for investigating the sintering process and its rate. We also discuss strategies for the design and rational fabrication of sinter-resistant catalysts. Finally, we showcase recent success in improving the thermal stability and thus sinter resistance of supported catalytic systems. [ABSTRACT FROM AUTHOR]

Supported metal catalysts are critical to many important chemical reactions, but the weak metal/support interaction is an obstacle to the success of remarkable catalytic performance. This paper reports rational-designed novel Pt supports, consisting of reduced graphene oxide sheets decorated with both Fe2O3 nanorods and N-dopants (denoted as Fe2O3/N-RGO), for Pt photodeposition driven by visible light in a controllable fashion. The 2-3 nm Pt nanocrystals primarily nucleated on rough Fe2O3 nanorods, and interacted strongly with special sites on the Fe2O3 surface using unsaturated vacant orbitals. At the same time, the accelerated photodegradation of undesirable PVP allowed the Pt nanocrystals with clean active sites. The supported Pt showed impressive activity and had a 7-times higher reaction rate constant (11.4 s-1 mg-1) towards 4-nitrophenol reduction, compared with that of free Pt, due to the synergetic effect within the whole Pt/Fe2O3/N-RGO catalysts and the doping of N atoms which acted as new metal-free catalytic centers in N-RGO sheets. We further demonstrated that the ternary catalyst could be easily removed through magnetic separation from the system. This new strategy is extendible to other heterogeneous catalysts with different components. [ABSTRACT FROM AUTHOR]

For TiO2-based photoanodes, the interfacial coupling between TiO2 and conductive materials (e.g., carbon) plays a vital role in determining the electron transfer efficiency and thus photoelectrical performance. In this paper, we describe a facile approach to effectively engineering the interfacial coupling between reduced graphene oxide (RGO) and TiO2 in well-designed one-dimensional (1D) RGO-wrapped TiO2 nanofibers, which act as ultrafast electron transfer bridges when implanted in photoanodes. The 3–5 nm RGO nanoshells were hybridized with TiO2 nanofibers as an electron donor component via d–π electron orbital overlap between C and Ti atoms, by adopting a thermal reduction at 450 °C. Remarkable photoelectric improvement, in terms of high photocurrent density by 2.2-fold and ultralow charge transfer resistance (Rct) by 0.2-fold, is ascribed to the interfacial charge transfer. Completely reduced RGO in RGO/TiO2 nanofibers was not necessary at the expense of their hydrophilicity, as it led to unexpected isolation in the photoanodes. The thermal reduction temperature of RGO/TiO2 nanofibers was found to be critical, and a maximal photocurrent density could be achieved by 2.7-fold at 530 °C. An excess of RGO/TiO2 nanofibers of more than 5 wt% had a degrading effect on the photoelectrical activity, largely due to the light-block effect and isolation in the matrix. This strategy provides new insight for tuning the intrinsic chemical and/or physical properties of well-designed semiconductor nanostructures with promising photoactivities in highly efficient photovoltaic devices. [ABSTRACT FROM AUTHOR]

Metal sintering poses significant challenges for developing reliable catalytic systems toward high-temperature reactions, particularly those based on metal clusters with sizes below 3 nm. In this work, electrospun dual-oxide fibril-in-tubes consisting of CeO 2 and Al 2 O 3 are rationally designed in an all-in-one manner, to stabilize 2.3 nm Pt clusters with a Tammann temperature (sintering onset temperature) lower than 250 °C. The abundant pores and channels effectively stabilize the Pt clusters physically, while the strong support, CeO 2 , with high adhesion, pins Pt clusters firmly, and the adjacent weak support, Al 2 O 3 , with low adhesion, provides energy barriers to prevent the clusters and emitted Pt atom(s) from moving across the support. Therefore, the ultra-close 2.3 nm Pt clusters, featuring an average nearest neighboring distance of only 2.1 nm, were carefully stabilized against sintering at temperatures exceeding 750 °C, even in oxidative and steam-containing environments. In addition, this catalytic system can efficiently and durably serve in diesel combustion, a high-temperature exothermic reaction, showing no activity decline after 5 cycles. This work provides a comprehensive understanding of sinter-resistant catalytic systems, and presents new insights for the development of advanced nanocatalysts., Competing Interests: The authors declare no competing interests., (This journal is © The Royal Society of Chemistry.)