A Dual Reactor for Isothermal Thermochemical Cycles of H2O/CO2 Co-Splitting Using La0.3Sr0.7Co0.7Fe0.3O3 as an Oxygen Carrier

Catalytic performance of La0.3Sr0.7Co0.7Fe0.3O3 (LSCF3773 or LSCF) catalyst for syngas production via two step thermochemical cycles of H2O and CO2 co-splitting was investigated. Oxygen storage capacity (OSC) was found to depend on reduction temperature, rather than the oxidation temperature. The highest oxygen vacancy (Δδ) was achieved when the reduction and oxidation temperature were both fixed at 900 °C with the feed ratio (H2O to CO2) of 3 to 1, with an increasing amount of CO2 in the feed mixture. CO productivity reached its plateau at high ratios of H2O to CO2 (1:1, 1:2, and 1:2.5), while the total productivities were reduced with the same ratios. This indicated the existence of a CO2 blockage, which was the result of either high Ea of CO2 dissociation or high Ea of CO desorption, resulting in the loss in active species. From the results, it can be concluded that H2O and CO2 splitting reactions were competitive reactions. Ea of H2O and CO2 splitting was estimated at 31.01 kJ/mol and 48.05 kJ/mol, respectively, which agreed with the results obtained from the experimentation of the effect of the oxidation temperature. A dual-reactors system was applied to provide a continuous product stream, where the operation mode was switched between the reduction and oxidation step. The isothermal thermochemical cycles process, where the reduction and oxidation were performed at the same temperature, was also carried out in order to increase the overall efficiency of the process. The optimal time for the reduction and oxidation step was found to be 30 min for each step, giving total productivity of the syngas mixture at 28,000 μmol/g, approximately.

Stalling chromophore synthesis of the fluorescent protein Venus reveals the molecular basis of the final oxidation step

Fluorescent proteins (FPs) have revolutionised the life sciences, but the chromophore maturation mechanism is still not fully understood. Here we photochemically trap maturation at a crucial stage and structurally characterise the intermediate.

Stalling chromophore maturation of the fluorescent protein Venus reveals the molecular basis of the final oxidation step

Fluorescent proteins (FPs) have revolutionised the life sciences but the mechanism of chromophore maturation is still not fully understood. Incorporation of a photo-responsive non-canonical amino acid within the chromophore stalls maturation of Venus, a yellow FP, at an intermediate stage; the crystal structure reveals the presence of O2 located above a dehydrated enolate imidazolone (I) ring, close to the strictly conserved Gly67 that occupies a twisted conformation. His148 adopts an “open” conformation, potentially allowing O2 access to the chromophore. Absorption spectroscopy supported by QM/MM simulations suggest that the first oxidation step involves formation of a hydroperoxyl intermediate in conjunction with dehydrogenation of the methylene bridge. A fully conjugated mature chromophore is formed through release of H2O2 upon irradiation of this intermediate, both in vitro and in vivo. The possibility of interrupting and photochemically restarting chromophore maturation, and the mechanistic insights opens up new approaches for engineering optically controlled fluorescent proteins.

Polyfunctional perovskite oxides optimized for efficient CO2 splitting against oxidative impurity via chemical looping

Via redox chemistry, chemical looping reduction of CO2 to CO provides a promising strategy for mitigating carbon emissions. However, it’s still challenging to directly reduce CO2/O2 mixture gas due to lack of effective oxygen carriers towards reductive C–O bond scission in the presence of strongly oxidative gas. Here, we report an autocatalytic strategy of polyfunctional perovskite oxides to achieve enhanced C–O bond activation and superior performance of methane driven syngas generation. The self-generated Ni nanoparticles, through Ni cations migrating from the bulk lattice to the surface of LaFeO3 perovskite under fast methane reduction, are identified as catalytically active sites for enhancing C-H activation in the methane oxidation step. The reduced Ni-LaFeO3 oxygen carrier features multifunctional active sites with Ni species for accelerating C–O activation and oxygen vacancies for O2 adsorption in the step of CO2 splitting with the presence of abundant O2. At 800℃, the 5 at.% Ni-LaFeO3 perovskite stably exhibited high performances during 100 redox cycles: 98% CO selectivity in the methane oxidation step, and 98.5% CO2 conversion in the step of CO2 splitting even with the presence of 25 at.% O2. This efficient and durable perovskite underpins an economic utilization of impure CO2 from various carbon sources with no requirement for energy-costing purifications.

Research on Performance Improvement of Photovoltaic Cells and Modules Based on Black Silicon

This paper mainly studied the electrical performance improvement of black silicon photovoltaic (PV) cells and modules. The electrical performance of the cells and modules matched with black silicon was optimized through three different experiments. Firstly, in the pre-cleaning step, the effect of lotion selection on the cell performance was studied. Compared with alkaline lotion, using acidic lotion on black silicon wafer can achieve an efficiency improvement of the black silicon cell by nearly 0.154%. Secondly, the influence of oxygen flux control of the thermal oxidation step on the improvement of cell efficiency was studied. The addition of the thermal oxidation step and its oxygen flux control resulted in an efficiency increase of the black silicon cell of nearly 0.11%. The most optimized volume control of the oxygen flux is at 2200 standard cubic centimeter per minute (SCCM). Finally, in the module packaging process, the selection of components will also greatly affect the performance of the black silicon PV module. The most reasonable selection of components can increase the output power of the black silicon PV module by 6.13 W. In a word, the technical indication of the electrical performance improvement suggested in this study plays an important guiding role in the actual production process.

Synthesis and properties of tetrathiafulvalenes bearing 6-aryl-1,4-dithiafulvenes

Novel multistage redox tetrathiafulvalenes (TTFs) bearing 6-aryl-1,4-dithiafulvene moieties were synthesized by palladium-catalyzed direct C–H arylation. In the presence of a catalytic amount of Pd(OAc)2, P(t-Bu3)·HBF4, and an excess of Cs2CO3, the C–H arylation of TTF with several aryl bromides bearing 1,3-dithiol-2-ylidenes took place efficiently to produce the corresponding π-conjugated molecules. We also succeeded in the estimation of the oxidation potentials and number of electrons involved in each oxidation step of the obtained compounds by digital simulations.

Implementation of an environmental decision support system for controlling the pre-oxidation step at a full-scale drinking water treatment plant

Drinking water treatment plants (DWTPs) face changes in raw water quality, and treatment needs to be adjusted to produce the best water quality at the minimum environmental cost. An environmental decision support system (EDSS) was developed for aiding DWTP operators in choosing the adequate permanganate dosing rate in the pre-oxidation step. To this end, multiple linear regression (MLR) and multi-layer perceptron (MLP) models are compared for choosing the best predictive model. Besides, a case-based reasoning (CBR) model was approached to provide the user with a distribution of solutions given similar operating conditions in the past. The predictive model consisted of an MLP and has been validated against historical data with sufficient good accuracy for the utility needs (R2 = 0.76 and RSE = 0.13 mg·L−1). The integration of the predictive and the CBR models in an EDSS gives the user an augmented decision-making capacity of the process and has great potential for both assisting experienced users and for training new personnel in deciding the operational set-point of the process.

Synthesis and Properties of Tetrathiafulvalenes Bearing 6-Aryl-1,4-dithiafulvenes

Novel multistage redox TTFs bearing 6-aryl-1,4-dithiafulvene moieties were synthesized by using the palladium-catalyzed direct C-H arylation. In the presence of a catalytic amount of Pd(OAc)2, P t Bu3•HBF4, and excess amount of Cs2CO3, the C-H arylation of TTF with several aryl bromides bearing 1,3-dithiol-2-ylidenes took place efficiently to produce the corresponding p-conjugation molecules. We also succeeded in estimation of the oxidation potentials and number of electrons involved in each oxidation step of the obtained compounds by the digital simulations.

Distonic radical anion species in cysteine oxidation processes

In contrast to the first reversible oxidation step being associated with sulfinate species, a novel distonic radical anion, •OS–CH2CH(NH2)–COO− has been identified with an inverted SOMO–HOMO energy order that can be restored via protonation.