Institute of Fundamental Technological Research

Photocatalytic CO2 reduction has emerged as a promising strategy for converting solar energy into valuable chemicals, capturing the attention of scientists across various disciplines. Organic and inorganic perovskites, particularly methylammonium lead bromide (MAPbBr3), have demonstrated potential in this field due to their remarkable visible-light response and carrier transport properties. However, the catalytic performance of pristine MAPbBr3 has been limited by severe charge recombination, hindering its applicability in photocatalytic systems. Here, we show that a MAPbBr3/Bi2WO6 (MA/BWO) heterojunction significantly enhances photocatalytic CO2 reduction performance compared to individual pristine MA or BWO. This enhancement is evidenced by the superior performance of the 25% MA/BWO composite, which exhibits CO and CH4 release rates of 1.82 μmol/g/h and 0.08 μmol/g/h, respectively. This improvement is attributed to the direct Z-scheme heterojunction formed between MAPbBr3 and Bi2WO6, which facilitates efficient charge separation and suppresses charge recombination. The results challenge the previous understanding of MAPbBr3-based photocatalysts and demonstrate a novel approach for developing highly active organic and inorganic perovskite photocatalysts. The successful application of the MA/BWO heterojunction in photocatalytic CO2 reduction expands the scope of organic and inorganic perovskites in the field of renewable energy conversion. By providing a broader perspective, our findings contribute to the ongoing efforts towards sustainable energy solutions, appealing

Transparent electrodes are vital for optoelectronic devices, but their development has been constrained by the limitations of existing materials such as indium tin oxide (ITO) and newer alternatives. All face issues of robustness, flexibility,conductivity, and stability in harsh environments. Addressing this challenge, we developed a flexible, low-cost titanium nitride (TiN) nanomesh transparent electrode showcasing exceptional acid−alkali resistance. The TiN nanomesh electrode, created by depositing a TiN coating on a naturally cracked gel film substrate via a sputtering method, maintains a stable electrical performance through thousands of bending cycles. It exhibits outstanding chemical stability, resisting strong acid and alkali corrosion, which is a key hurdle for current electrodes when in contact with acidic/alkaline materials and solvents during device fabrication. This, coupled with superior light transmission and conductivity (88% at 550 nm with a sheet resistance of ∼200 Ω/sq), challenges the reliance on conventional materials. Our TiN nanomesh electrode,successfully applied in electric heaters and electrically controlled thermochromic devices, offers broad potential beyond harsh environment applications. It enables alternative possibilities for the design and fabrication of future optoelectronics for advancements in this pivotal field.

transparent electrode, titanium nitride, flexible, corrosion resistant, mesh, smart window

Two-dimensional polystyrene sphere opals are important materials for nanotechnology applications and fundamental nanoscience research. They are a facile and inexpensive nanofabrication tool, but the quality factor of these opals has drastic differences between reports. Additives like ethanol, ions, and organic molecules in the aqueous particle spreading solution are known to affect the quality factor and growth efficiency of the produced opals. However, a systematic study on the effect and optimization of some of the most effective additives has not been reported until now. Here, we investigate the influence of additives on the growth efficiency and quality factor of such monolayers formed at the air−water interface without the use of a Langmuir−Blodgett trough. The additives induced large variations in the monolayer quality factor and growth efficiency, and we found that the ideal additive content of the spreading agents is 30 wt % < cethanol < 70 wt %, 0 < cHd 2SOd 4 < 30.5 mM, and 0 < csty < 255.0 mM. This study provides a guideline for the rational composition and additive content of the spreading solution to obtain high-quality two-dimensional opals for further applications in nanofabrication and photonics and will enable researchers and application engineers to produce standardized nanofabrication materials.

A simple and inexpensive method for the controlled loading of silica particles with dyes and nanocrystals is presented. Polydiallyldimethylammonium chloride is used as a positively charged bridge to facilitate electrostatic adsorption of negatively charged dyes onto negatively charged silica microspheres. The particles are subsequently coated with a further silica shell to protect the dyes against chemical degradation and leakage and this shell affords a unform particle surface independent of its doping. This encapsulation method is highly versatile and can be extended to doping with semiconductor nanocrystals, which we demonstrate using CdSe/ZnS core/shell quantum dots. The synthesis steps and end products are characterized with electron microscopy, optical spectroscopy and the electrokinetic potential of the colloidal suspensions. We show that the particles adapt the optical properties of their dopants and are resistant to degradation, dopant leakage and show reasonable emission even at acidic pH values due to the protective shell.

Silica particles, Dye, Quantum dot, Polydiallyldimethylammonium chloride, Doping

We propose a simple and inexpensive SiO2 submicron particle synthesis method based on a PTFE helical capillary microreactor. The device is based on Dean flow mediated, ultrafast mixing of two liquid phases in a microfluidic spiral pipe. Excellent control of particle size between 100 nm and 600 nm and narrow polydispersity can be achieved by controlling the device and process parameters. Numerical simulations are performed to determine the optimal device dimensions. In the mother liquor the silica particles exhibit zeta potentials < -60 mV, rendering them very stable even at high particle volume fractions. The current device typically produces around 0.234 g/h of the silica particles.

SiO2 particle synthesis, continuous flow synthesis, helical capillary microreactor

Semiconducting ternary metal oxide thin films exhibit a promising application for solarenergy conversion. However, the efficiency of the conversion is still limited by a band gapof a emiconductor, which determines an obtainable internal photovoltage for solar watersplitting. In this report the tunability of the tin tungstate band gap by O2 partial pressurecontrol in the magnetron co-sputtering process is shown. A deficiency in the Sn concentration increases the optical band gap of tin ungstate thin films. The optimum band gap of 1.7 eV for tin tungstate films is achieved for a Sn to W ratio at unity, which establishes thehighest photoelectrochemical activity. In particular, a maximum photocurrent density of 0.375 mA cm^2 at 1.23 VRHE and the lowest reported onset potential of -0.24 VRHE for SnWO4 thin films without any co-catalyst are achieved. Finally, we demonstrate that a Ni protection layer on the SnWO4 thin film enhances the photoelectrochemical stability, which isof paramount importance for application.

thin film, tin tungstate, reactive magnetron sputtering, photocurrent density, thickness band gap

There is an urgent need for new materials that can catalyze or drive the photoelectrochemical (PEC) conversion of solar energy into chemical energy, i.e. solar fuels. Copper bismuth oxide (CBO) is a promising photocathode material for the photochemical reduction of water. Here, we systematically control the stoichiometry of CBO thin films prepared by reactive, direct-current magnetron co-sputtering from metallic Bi and Cu targets. The intrinsic photophysical and PEC material properties are investigated and evaluated in order to determine the optimum composition for hydrogen formation. Changing the stoichiometry of the films reveals a dramatic change in the optical band gap and crystal structure of CBO. The largest photocurrent density was achieved for a copper-to-bismuth ion ratio of 0.53, close to the CuBi2O4 stoichiometry, which yielded Jph = − 0.48 mA cm^−2 at 0 VRHE (RHE = reversible hydrogen electrode). This is the highest value to date for the photochemical reduction of water with CuBi2O4 without an externally applied bias. The absorbed photon-to-current efficiency and the photostability of the films in neutral and alkaline electrolytes were also investigated.

CuBi2O4, copper bismuth oxide, water reduction, water splitting, photocathode, magnetron sputtering