A facile and general method has been developed to fabricate oxygen vacancies on perovskite SrTiO3 (STO) nanocrystals through a controllable solid-state reaction of NaBH4 and SrTiO3 nanocrystals. STO samples with tunable color, oxygen vacancy concentration on nanocrystal surface have been synthesized. TEM results reveal that these STO samples have a crystalline core/amorphous shell structure (SrTiO3@SrTiO3-x). XPS and EPR results disclose that the oxygen vacancy concentration increases with the increase of reaction time and temperature. The concentration of oxygen vacancies calculated from TGA data, could reach 5.07% (atom) in this study. UV-vis spectra and photocatalytic results indicate that oxygen vacancies on STO surface play an important role in influencing the light absorption and photocatalytic performance. However, an excess amount of oxygen vacancies leads to a decrease of photocatalytic performance. The optimal photocatalytic activity for H2 production under UV-vis irradiation is up to 2.2 mmol h(-1) g(-1), which is about 2.3 times than the original SrTiO3, corresponding to 3.28% (atom) of oxygen vacancy concentration.

Photocatalytic water purification utilizes light to degrade the contaminants in water and may enjoy many merits of microfluidics technology such as fine flow control, large surface-area-to-volume ratio and self-refreshing of reaction surface. Although a number of microfluidic reactors have been reported for photocatalysis, there is still a lack of a comprehensive review. This article aims to identify the physical mechanisms that underpin the synergy of microfluidics and photocatalysis, and, based on which, to review the reported microfluidic photocatalytic reactors. These microreactors help overcome different problems in bulk reactors such as photon transfer limitation, mass transfer limitation, oxygen deficiency, and lack of reaction pathway control. They may be scaled up for large-throughput industrial applications of water processing and may also find niche applications in rapid screening and standardized tests of photocatalysts.

Food production in green crops is severely limited by low activity and poor specificity of D-ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) in natural photosynthesis (NPS). This work presents a scientific solution to overcome this problem by immobilizing RuBisCO into a microfluidic reactor, which demonstrates a continuous production of glucose precursor at 13.8 μmol g −1 RuBisCO min −1 from CO 2 and ribulose-1,5-bisphosphate. Experiments show that the RuBisCO immobilization significantly enhances enzyme stabilities (7.2 folds in storage stability, 6.7 folds in thermal stability), and also improves the reusability (90.4% activity retained after 5 cycles of reuse and 78.5% after 10 cycles). This work mimics the NPS pathway with scalable microreactors for continuous synthesis of glucose precursor using very small amount of RuBisCO. Although still far from industrial production, this work demonstrates artificial synthesis of basic food materials by replicating the light-independent reactions of NPS, which may hold the key to food crisis relief and future space colonization.

Metamaterials, which are composed of metallic and dielectric subwavelength structures arranged in periodic array, are artifi cial materials with the permittivity or permeability less than that of vacuum or with negative values unattainable in nature. [1][2][3] Due to their unique electromagnetic properties, metamaterials have been widely used in many applications, such as sensors, superlenses, miniature antennas, and invisible cloaks. [4][5][6][7] Recently, metamaterial-based perfect absorbers have been attracted considerable attentions and various types of terahertz metamaterial absorbers have been reported. For example, Landy et al. presented a polarization-insensitive metamaterial absorber composed of metallic split ring resonators and cutting wires with singe-band absorption. [ 8 ] X.-J. He et al. proposed a dual-band metamaterial absorber made of two stacked metallic cross resonators and a lower metallic ground plane, separated by an isolation material spacer. [ 9 ] Cheng-Wen Cheng presented wide-angle polarization independent infrared dual band absorbers based on metallic multisized disk arrays. [ 10 ] Yanxia Cui proposed a sawtooth anisotropic metamaterial slab absorber for Transverse Magnetic (TM) polarized light with absorptivity higher than 95% covering a waveband ranging from 3 to 5.5 μ m. [ 11 ] However, current metamaterial absorbers suffer from many disadvantages such as narrow operating waveband, sensitivity to the polarization state of the incident light, narrow accepted angles and a fi xed azimuthal angle, which greatly limit their potential applications to spectroscopic detection and phase imaging. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Hence, a light absorbing device that is broadband, wide-angle and insensitive to the incident light polarization state is urgently needed for its applications in areas mentioned above. In this letter, we propose a two-dimensional (2D) pyramidal shape metamaterial-based absorber. In comparison with previous designs, this pyramid metamaterial absorber has a very high absorptivity performance that is polarization-insensitive, wide-angle and omni-directional at full infrared waveband.The proposed two-dimensional pyramid absorber is composed of alternating metallic and dielectric thin fi lms as shown in the insets of Figure 1 a. The metal thin fi lm is made of gold with thickness t m = 10 nm; dielectric thin fi lm is made of germanium with thickness t d = 190 nm. The total number of metal/dielectric pairs ( N) is 15. These multiple thin fi lm layers are carved into a pyramid structure for each unite cell. The periods of the unit cell in both x and y directions are 1600 nm. A gold fi lm with a thickness ( t = 100 nm) is added under the pyramid metamaterial absorber to block any incident light transmission. The optimized pyramid absorber structure was obtained through fi nite-difference time-domain (FDTD) simulations (Lumerical Inc.). [ 24 ] The material properties of gold and germanium were chosen from the software database-Gold Palik and Ger...

Surface plasmon polaritons (SPPs) has attracted great attention in the last decade and recently it has been successfully applied to nanolithography due to its ability of beyond diffraction limit. This article reviews the recent development in plasmonic nanolithography, which is considered as one of the most remarkable technology for next-generation nanolithography. Nanolithography experiments were highlighted on the basis of SPPs effect. Three types of plasmonic nanolithography methods: contact nanolithography, planar lens imaging nanolithography, and direct writing nanolithography were reviewed in detail, and their advantages and shortages are analyzed and compared, respectively. Finally, the development trend of plasmonic nanolithography is suggested.

Recent years have witnessed an increasing interest in highly-efficient absorbers of visible light for the conversion of solar energy into electrochemical energy. This study presents a TiO2-Au bilayer that consists of a rough Au film under a TiO2 film, which aims to enhance the photocurrent of TiO2 over the whole visible region and may be the first attempt to use rough Au films to sensitize TiO2. Experiments show that the bilayer structure gives the optimal optical and photoelectrochemical performance when the TiO2 layer is 30 nm thick and the Au film is 100 nm, measuring the absorption 80–90% over 400–800 nm and the photocurrent intensity of 15 μA·cm−2, much better than those of the TiO2-AuNP hybrid (i.e., Au nanoparticle covered by the TiO2 film) and the bare TiO2 film. The superior properties of the TiO2-Au bilayer can be attributed to the rough Au film as the plasmonic visible-light sensitizer and the photoactive TiO2 film as the electron accepter. As the Au film is fully covered by the TiO2 film, the TiO2-Au bilayer avoids the photocorrosion and leakage of Au materials and is expected to be stable for long-term operation, making it an excellent photoelectrode for the conversion of solar energy into electrochemical energy in the applications of water splitting, photocatalysis and photosynthesis.

We present a beam shaping technique in controlling the complex amplitude of an optical beam. The constraint on the amplitude of the output beam in the Gerchberg-Saxton algorithm is replaced with constraints both on the amplitude and phase of the output beam in the proposed method. The total areas of the constrained regions and free regions on the complex amplitude of the output beam in the proposed method are maintained. An output beam with arbitrary complex amplitude can be realized with the proposed method. The computing result from the proposed method is a phase-only distribution, which can be fabricated as diffractive optical element for higher diffraction efficiency. Both simulations and experiments are present and the effectiveness of the proposed method is verified.

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