Switchable Kirigami Structures as Window Envelopes for Energy-Efficient Buildings.

Efficient regulation of thermal radiation is an effective way to conserve energy consumption of buildings. Because windows are the least energy-efficient part of buildings, their thermal radiation regulation is highly demanded, especially in the changing environment, but is still a challenge. Here, by employing a kirigami structure, we design a variable-angle thermal reflector as a transparent envelope of windows for their thermal radiation modulation. The envelope can be easily switched between heating and cooling modes by loading different pre-stresses, which endow the envelope windows with the ability of temperature regulation, and the interior temperature of a building model can be reduced by ~3.3 °C under cooling mode and increased by ~3.9 °C under heating mode in the outdoor test. The improved thermal management of windows by the adaptive envelope provides an extra heating, ventilation, and air-conditioning energy savings percentage of 13% to 29% per year for buildings located in different climate zones around the world, making the kirigami envelope windows a promising way for energy-saving utilization.

Efficient Near-Infrared PbS Quantum Dot Solar Cells Employing Hydrogenated In2 O3 Transparent Electrode.

Infrared solar cells are regarded as candidates for expanding the solar spectrum of c-Si cells, and the window electrodes are usually transparent conductive oxide (TCO) such as widely used indium tin oxide material. However, due to the low transmittance of the TCO in the near-infrared region, most near-infrared light cannot penetrate the electrode and be absorbed by the active layer. Here, the propose a simple procedure to fabricate the window materials with high near-infrared transmittance and high electrical conductivity, namely the hydrogen-doped indium oxide (IHO) films prepared by room temperature magnetron sputtering. The low-temperature annealed IHO conductive electrodes exhibit high mobility of 98 cm2 V-1 s-1 and high infrared transmittance of 85.2% at 1300 nm, which endows the lead quantum dot infrared solar cell with an improved short-circuit current density of 37.2 mA cm-2 and external quantum efficiency of 70.22% at 1280 nm. The proposed preparation process is simple and compatible with existing production lines, which gifts the IHO transparent conductive film great potential in broad applications that simultaneously require high infrared transmittance and high conductivity.

Outstanding comprehensive performance versus facile synthesis: Constructing core and shell-interchangeable nanocomposites as microwave absorber.

It is still a great challenge to develop high-performance microwave absorption materials (MAMs). Herein, we first proved the excellent synergistic effect of Fe3O4/MoS2 heterostructure based on the theoretical calculations. To effectively utilize the synergistic effect and morphology, core and shell-interchangeable Fe3O4@MoS2 and MoS2@Fe3O4 nanocomposites (NCs) were elaborately constructed. By controlling the hydrothermal temperature, different MoS2 morphologies and contents of Fe3O4@MoS2 NCs were produced, which simultaneously displayed the optimal reflection loss (RL) values (~-50 dB), broad absorption bandwidth (⩾5.0GHz) and high chemical stabilities. With the synthesis temperature increasing from 170 °C to 200 °C, their outstanding microwave absorption (MA) capabilities moved towards the high frequency region and thin matching thickness. Impressively, the Fe3O4@MoS2 obtained at 200 °C presented a minimum RL value of -50.75 dB with the thickness of 2.90 mm and an absorption bandwidth of 5.0 GHz with the thickness of 1.71 mm, and the excellent MA capabilities (RL values <-30 dB) with the low matching thicknesses (<2 mm) could be observed in the frequency range of X and Ku bands. Moreover, compared to the reverse structure MoS2@Fe3O4, the core@shell structure Fe3O4@MoS2 exhibited evidently superior MA comprehensive properties in terms of low optimal RL value, broad absorption bandwidth and high chemical stability, which could be ascribed to the improved impedance matching and microwave attenuation characteristics. Generally, the proposed flower-like core@shell structure Fe3O4@MoS2 NCs presented very extraordinary MA comprehensive properties, which were very attractive candidates for high-performance MAMs.

Water-assisted and controllable synthesis of core/shell/shell structured carbon-based nanohybrids, and their magnetic and microwave absorption properties.

By controlling the pyrolysis temperature, core/shell/shell structured Fe/Fe5C2/carbon nanotube bundles (Fe/Fe5C2/CNTBs), Fe/Fe3C/helical carbon nanotubes (Fe/Fe3C/HCNTs) and Fe/Fe3C/chain-like carbon nanospheres (Fe/Fe3C/CCNSs) with high encapsulation efficiency could be selectively synthesized in large-scale by water-assisted chemical vapor deposition method. Water vapor was proved to play an important role in the growth process. Because of α-Fe nanoparticles tightly wrapped by two layers, the obtained core/shell/shell structured nanohybrids showed high stabilities and good magnetic properties. The minimum reflection loss values of the as-prepared nanohybrids reached approximately -15.0, -46.3 and -37.1 dB, respectively. The excellent microwave absorption properties of the as-prepared core/shell/shell structured nanohybrids were considered to the quarter-wavelength matching model. Moreover, the possible enhanced microwave absorption mechanism of the as-prepared Fe/Fe3C/HCNTs and Fe/Fe3C/CCNSs were discussed in details. Therefore, we proposed a simple, inexpensive and environment-benign strategy for the synthesis of core/shell/shell structured carbon-based nanohybrids, exhibiting a promising prospect as high performance microwave absorbing materials.