Research status, challenges and future prospects of renewable synthetic fuel catalysts for CO2 photocatalytic reduction conversion.

In recent years, with global climate change, the utilization of carbon dioxide as a resource has become an important goal of human society to achieve carbon peaking and carbon neutrality. Among them, the catalytic conversion of carbon dioxide to generate renewable fuels has received great attention. As one of these methods, photocatalysis has its unique properties and mechanism, which can only rely on sunlight without inputting other energy. It is an emerging discipline with great development prospects. The core of photocatalysis lies in the development of photocatalysts with high activity, high selectivity, low cost, and high durability. This review first introduces the background and mechanism of photocatalysis, then introduces various types of photocatalysts based on different substrates, and analyzes the methods and mechanisms to improve the activity and selectivity of photocatalysts. Finally, combining the plasmon effect with photocatalysis, the review analyzes the promoting effect of the plasmon effect on the photocatalytic carbon dioxide synthesis of renewable fuels, which provides a new idea for it.

Highly efficient production of bacterial cellulose from corn stover total hydrolysate by Enterobacter sp. FY-07.

Bacterial cellulose (BC) has a huge global market due to its excellent properties and wide range of applications. However, due to high production costs, low productivity, and unsatisfactory scale-up production, industrialisation has been slow. Herein, stabilization of strain, optimisation of culture conditions, and a cheap carbon source were combined to achieve highly efficient, low-cost, large-scale BC production in 20 L containers. Optimisation of culture conditions increased both BC productivity and sugar conversion ratio significantly, from 2.08 g/L/day and 9.78% to 17.13 g/L/day and 70.31%, respectively. Furthermore, BC productivity and sugar conversion ratio reached 13.96 g/L/day and 85.50% using corn stover total hydrolysate as carbon source. The low-cost, facile, and highly efficient process can generate large quantities of BC, and could promote industrialisation of BC production.

Production of nisin-containing bacterial cellulose nanomaterials with antimicrobial properties through co-culturing Enterobacter sp. FY-07 and Lactococcus lactis N8.

Bacterial cellulose (BC) is used in various fields for its unique physical properties, but does not have the antimicrobial properties needed for the food and biomedical industries. Co-culture fermentation is a method commonly used in biotechnology to address high costs. A nisin-containing BC film (BC-N) was obtained by co-cultivating the BC-producing strain Enterobacter sp. FY-07 with the nisin-producing strain Lactococcus lactis N8. The physical properties of BC-N were similar those of BC, but the BC-N film had a specific strong inhibitory effect on Gram-positive bacteria. The antibacterial mechanism of BC-N was pore formation, but the obtained BC-N film had no significant impact on mammalian cell viability. This study provides a low-cost, facile and efficient technique to confer BC with antimicrobial properties. This strategy can be applied to introduce other functions into BC, and develop applications for BC polymers.

In situ production of bacterial cellulose/xanthan gum nanocomposites with enhanced productivity and properties using Enterobacter sp. FY-07.

While bacterial cellulose (BC) is a widely used, high-value product, its industrial production is hindered by the limited properties and productivity. Herein, by combining optimized fermentation methods and adding XG for in situ modification during submerged fermentation of Enterobacter sp. FY-07 (FY-07), homogeneously modified BC/xanthan gum (XG) nanocomposites with enhanced productivity and properties were obtained. The relationship between BC productivity and the contact area between the bacteria and objects was explored. The productivity of BC reached 3.2 g/L/d under optimal conditions. Compared to BC, the BC/XG nanocomposite exhibited coarser fibers along with significantly higher hardness, chewiness, resilience, and tensile strength, making the nanocomposite more suitable for food and other applications. The findings provide a low-cost, simple, and efficient strategy to improve the properties and productivity of BC. This work has significant implications for the in situ modification and production of BC in the biopolymer industry.

Gradient Engineered Light Absorption Layer for Enhanced Carrier Separation Efficiency in Perovskite Solar Cells.

Carrier transport behavior in the perovskite light absorption layer significantly impacts the performance of perovskite solar cells (PSCs). In this work, reduced carrier recombination losses were achieved by the design of a band structure in perovskite materials. An ultrathin (PbI2/PbBr2)n film with a gradient thickness ratio was deposited as the lead halide precursor layer by a thermal evaporation method, and PSCs with a gradient band structure in the perovskite absorption layer were fabricated by a two-step method in ambient atmosphere. For comparison, PSCs with homogeneous perovskite materials of MAPbI3 and MAPbIxBr3 - x were fabricated as well. It is found that the gradient type-II band structure greatly reduces the carrier lifetime and enhances the carrier separation efficiency. As a result, the PSCs with a gradient band structure exhibit an average power conversion efficiency of 17.5%, which is 1-2% higher than that of traditional PSCs. This work provides a novel method for developing high-efficiency PSCs.

Microbial enhanced oil recovery through deep profile control using a conditional bacterial cellulose-producing strain derived from Enterobacter sp. FY-07.

BACKGROUND: Heterogeneity of oil-bearing formations is one of major contributors to low oil recovery efficiency globally. Long-term water flooding will aggravate this heterogeneity by resulting in many large channels during the exploitation process. Thus, injected water quickly flows through these large channels rather than oil-bearing areas, which ultimately leads to low oil recovery. This problem can be solved by profile control using polymer plugging. However, non-deep profile control caused by premature plugging is the main challenge. Here, a conditional bacterial cellulose-producing strain, namely Enterobacter sp. FY-0701, was constructed for deep profile control to solve the problem of premature plugging. Its deep profile control and oil displacement capabilities were subsequently identified and assessed. RESULTS: The conditional bacterial cellulose-producing strain Enterobacter sp. FY-0701 was constructed by knocking out a copy of fructose-1, 6-bisphosphatase (FBP) encoding gene in Enterobacter sp. FY-07. Scanning electron microscope observation showed this strain produced bacterial cellulose using glucose rather than glycerol as the sole carbon source. Bacterial concentration and cellulose production at different locations in core experiments indicated that the plugging position of FY-0701 was deeper than that of FY-07. Moreover, enhanced oil recovery by FY-0701 was 12.09%, being 3.86% higher than that by FY-07 in the subsequent water flooding process. CONCLUSIONS: To our knowledge, this is the first report of conditional biopolymer-producing strains used in microbial enhance oil recovery (MEOR). Our results demonstrated that the conditional bacterial cellulose-producing strain can in situ produce biopolymer far from injection wells and plugs large channels, which increased the sweep volume of injection water and enhance oil recovery. The construction of this strain provides an alternative strategy for using biopolymers in MEOR.

Improved Open-Circuit Voltage and Repeatability of Perovskite Cells Based on Double-Layer Lead Halide Precursors Fabricated by a Vapor-Assisted Method.

Highly repeatable fabrication of compact perovskite films is crucial for large-area perovskite cells (PSCs) in commercial applications. In this work, a vapor-assisted method with the combination of spin-coating and thermal evaporation is employed to fabricate the double-layer PbI2/PbIxBr(2-x) precursor. It is found that surface morphologies of perovskite films could be tailored through tuning the spin-coating speed (the first precursor layer) and chemical compositions (the second precursor layer). The continuous pinhole-free perovskite films are successfully fabricated by double-layer PbI2/PbBr2 precursors. The open-circuit voltages of all the corresponding cells exceed 1.00 V, showing an average value of 1.02 V. The high mean voltage and small variation reveals high repeatability of this method. This work provides a potential method to achieve large-area and high-efficiency PSCs.

Production of bacterial cellulose hydrogels with tailored crystallinity from Enterobacter sp. FY-07 by the controlled expression of colanic acid synthetic genes.

Hydrogels exhibit smart three-dimensional networks and extraordinary water-absorbing ability. To improve the water-holding capacity of bacterial cellulose hydrogels, the expression of a biosynthetic gene cluster of colanic acid, a water-soluble polysaccharide, was induced in Enterobacter sp. FY-07, which produces an abundance of bacterial cellulose hydrogel under aerobic and anaerobic fermentation conditions. The results indicated that in situ modified bacterial cellulose hydrogels with different crystallinities, rheological properties and water-holding capacities were produced by cultivating the engineered strain Enterobacter sp. FY-07::tac under different inducing conditions. The water-holding capacity of the modified bacterial cellulose hydrogel was enhanced by more than 1.7 fold compared to the hydrogel produced by Enterobacter sp. FY-07, and the networks of the modified bacterial cellulose hydrogel were densified but still clear. These results suggest that this in situ modification strategy endows bacterial cellulose hydrogels with improved properties and potentially expands their applications in biomedical fields and the food industry.

Nonuniform Effect of Carrier Separation Efficiency and Light Absorption in Type-II Perovskite Nanowire Solar Cells.

Coaxial structures exhibit great potential for the application of high-efficiency solar cells due to the novel mechanism of radial charge separation. Here, we intensively investigate the nonuniform effect of carrier separation efficiency (CSE) and light absorption in perovskite-based type-II coaxial nanowire solar cells (ZnO/CH3NH3PbI3). Results show that the CSE rapidly decreases along the radial direction in the shell, and the value at the outer side becomes extremely low for the thick shell. Besides, the position of the main light absorption gradually moves to the outer side with the increase of the shell thickness. As a result, the external quantum efficiency shows a positional dependence with a maximal value close to the border of the nanowire. Eventually, in our case, it is found that the maximal power conversion efficiency of the solar cells reduces from 19.5 to 17.9% under the effect of the nonuniformity of CSE and light absorption. This work provides a basis for the design of high-efficiency solar cells, especially type-II nanowire solar cells.

Enhanced magneto-optical effects in composite coaxial nanowires embedded with Ag nanoparticles.

Nanostructures decorated with noble metal nanoparticles (NPs) exhibit potential for use in highly sensitive optoelectronic devices through the localized surface plasmon resonance (LSPR) effect. In this study, Faraday rotation was significantly enhanced through the structural optimization of ferromagnetic (FM)/semiconductor composite nanostructures. Experimental and theoretical results revealed that the position of noble metal NPs significantly influenced the coupling of the LSPR-enhanced electromagnetic field with FM materials. Furthermore, nanostructures embedded with noble metals demonstrated an improved capability to efficiently use the electromagnetic field compared to other structures. The Faraday rotation of ZnO/Ag(NPs)/Fe was enhanced 58 fold compared to that of the ZnO(film)/Fe. This work provides a basis for the design of nanoarchitectures for miniaturized high-performance magneto-optical devices.

Facile synthesis of composition-tuned ZnO/Zn x Cd1-x Se nanowires for photovoltaic applications.

ZnO/Zn x Cd1-x Se coaxial nanowires (NWs) have been successfully synthesized by combining chemical vapor deposition with a facile alternant physical deposition method. The shell composition x can be precisely tuned in the whole region (0 ≤ x ≤ 1) by adjusting growth time ratio of ZnSe to CdSe. As a result, the effective bandgaps of coaxial nanowires were conveniently modified from 1.85 eV to 2.58 eV, almost covering the entire visible spectrum. It was also found that annealing treatment was in favor of forming the mixed crystal and improving crystal quality. An optimal temperature of 350°C was obtained according to our experimental results. Additionally, time resolved photo-luminescence spectra revealed the longest carrier lifetime in ZnO/CdSe coaxial nanowires. As a result, the ZnO/CdSe nanowire cell acquired the maximal conversion efficiency of 2.01%. This work shall pave a way towards facile synthesis of ternary alloys for photovoltaic applications.

Performance evaluation of multi-junction solar cells by spatially resolved electroluminescence microscopy.

An electroluminescence microscopy combined with a spectroscopy was developed to visually analyze multi-junction solar cells. Triple-junction solar cells with different conversion efficiencies were characterized by using this system. The results showed that the mechanical damages and material defects in solar cells can be clearly distinguished, indicating a high-resolution imaging. The external quantum efficiency (EQE) measurements demonstrated that different types of defects or damages impacted cell performance in various degrees and the electric leakage mostly degraded the EQE. Meanwhile, we analyzed the relationship between electroluminescence intensity and short-circuit current density J SC. The results indicated that the gray value of the electroluminescence image corresponding to the intensity was almost proportional to J SC. This technology provides a potential way to evaluate the current matching status of multi-junction solar cells.