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To study the antibacterial efficacy of metallic Ag nanoparticle/titania (Ag‐NP)/TiO2 composite thin films against Escherichia coli (ATCC 25922), COMP‐Agn with various amounts of Ag (10 mol% ≤ n ≤ 80 mol%) are fabricated on a quartz glass substrate at 600 °C using the molecular precursor method. The films are characterized by X‐ray diffraction, X‐ray photoelectron, scanning electron microscopy, transmission electron microscopy, photoluminescence, and UVvis techniques. The analysis reveals that the films are composed of metallic Ag‐NPs embedded in a mixture of anatase and rutile matrix, with a volumetric fraction of Ag ranging from 0.18 to 0.68. The antibacterial activity of the TiO2 thin film and COMP‐Agn are determined by disk diffusion and viable cell count methods. Neither pure TiO2 nor pure Ag films exhibit any discernible antibacterial under dark and visible light. The antibacterial of Ag content in composite films is observed to persist for a maximum increase of 70%. The model is proposed on the basis of photoexcited electron transfer from Ag NPs to the TiO2 conduction band of COMP‐Agn, which clarifies the main factors affecting the photoresponse and the excellent response to visible light via surface plasmon resonance. [ABSTRACT FROM AUTHOR]

The TiO2 thin film, Ag NP and three Ag‐NP/TiO2 composite thin films (COMP‐Agn;n = 20, 50, and 75 Ag mol%) were successfully fabricated on quartz glass. The optical properties of the composite electrodes were investigated, and the results indicate a surface plasmonic resonance peak at 410 nm while the electrical resistivity of the composite thin films improved up to 6.9 × 10−5 Ω cm. The photo‐response threshold of the Ag‐NP/TiO2 composite thin films was enhanced and shifted into the visible and near‐infrared when the chlorophyll dye was adsorbed onto them. The hall effect was performed on the fabricated thin films and the charge carrier concentrate value confirmed that the Ag/TiO2 with Ag concentrate >45% are found to be p‐type. The n‐types were observed till the Ag content in TiO2 was increased up to 45 mol%. COMP‐Ag75 has a charge carrier concentration of 1.3 × 10−19 cm−3 as a p‐type electrode was then employed to construct a p‐DSSC. Such enhancement on photovoltaic activity can be attributed to the generated Z‐scheme system in the anatase/rutile phase‐junction Ag/TiO2 photocathode enhances the separation, diffusion, and transformation of electron/hole pairs inside the structure. This p‐DSSC exhibits a photon‐electrical conversion efficiency (PCE) of 0.37%. The PCE recorded is equal to or greater than those of traditional high‐efficiency n‐DSSCs. This allows the creation of a new generation of photocathodic p‐DSSCs with previously unheard‐of unprecedentedly high concentrations of Ag (up to 80 mol%) evenly scattered in a TiO2 matrix, and this efficacy is the highest ever reported for a p‐type working Ag/TiO2/chlorophyll/iodine electrode. This may enable the use of this electrode as a component of photosensitizer tandem devices. Highlights: ▪The 75 mol% Ag/TiO2 composited higher conductive p‐type electrode was fabricated.▪The Electrode found to have a visible plasmon peak at 410 nm and electrical conductivity of 6.7 × 10−5 cm.▪This p‐type electrode was then employed as a working electrode to construct a p‐DSSC.▪This p‐DSSC exhibits a photon‐electrical conversion efficiency (PCE) of 0.37%.▪Although the PCE is lower, this electrode can be a component of photosensitizer tandem devices. [ABSTRACT FROM AUTHOR]

The article discusses the enhancement of the photo-response threshold in Ag-NP/TiO2 composite thin films by adsorbing chlorophyll dye extracted from mopane leaves onto them. This advancement allows for the creation of photocathodic p-DSSCs with high concentrations of Ag evenly scattered in a TiO2 matrix. The efficacy of this electrode is the highest ever reported for a p-type working Ag/TiO2/chlorophyll/iodine electrode, which may have potential applications in photo-sensitizer tandem devices. The article is authored by Likius S. Daniel, Rocha T. Kaffer, Loini M. Kalipi, Ateeq Rahman, Mbela Kalengay, and Veikko Uahengo. [Extracted from the article]

Herein, a colorimetric sensor (L) based on a naphthyl derivative bearing hydrazone receptors was synthesized via a one-step reaction process, and its recognition properties towards biologically important anions in an acetonitrile–water mixture were investigated by naked-eye observation and UV-Vis and 1H NMR spectroscopy. The molar addition of anions, such as TBAF−, TBAOH−, TBACN− and TBAAcO−, induced a significant red shift in the charge transfer band (Δλ = 73 nm, from 337 nm to 410 nm), in agreement with visible "naked eye" detectable colorimetric activities; in addition, soaked-in-L paper strips were prepared, which could significantly discriminate cyanide (KCN) and hydroxide (NaOH) ions dissolved in tap water via the litmus test method. This study was complemented by density functional theory computations to gain more insight into the interaction between L and anions. [ABSTRACT FROM AUTHOR]

A benzotrithiophenes (BTT) based colorimetric sensor (2) was synthesized via a simple one-step reaction process, and its recognition properties towards several biologically important anions and cations were investigated by naked eye observation and spectroscopic methods of UV-vis and 1H NMR analysis in DMSO. The molar addition of anions such as F−, AcO−, and H2PO4- induced a marked red shift of the charge transfer band (Δλ=94 nm, from 440 nm to 534 nm) concomitant with a clearly visible “naked eye” detectable colorimetric activities (from orange to pink). However, the molar addition of H2PO4- did not induce significant spectral changes, compared to F− and AcO−. Furthermore, the molar addition of Hg2+ to 2 resulted in hypochromic shift at 440 nm and the eventual disappearance of a low energy band at 534 nm, concomitant with the colorimetric activities (from orange to yellow). Moreover, both spectral and color changes induced by the addition of anions (F− and AcO−) were all reversible by the molar addition of metal cations of 3d5–10. The reversibility properties triggered the logic operation studies, and, subsequently, the complementary IMP/INH logic functions based on color and spectral switching (ON/OFF) were confirmed. Conclusively, 2 can thus be utilized as a colorimetric molecular switch modulated by AcO−/MII. [ABSTRACT FROM AUTHOR]

The Ag-nanoparticles (Ag-NP)/TiO2 composite thin films with various amounts of Ag (10 mol% ≤ n ≤ 80 mol%) were examined as a potential photocatalyst by decoloration reaction of methylene blue (MB) in an aqueous solution. These composite thin films of ca. 100 nm thickness were fabricated by the MPM at 600 ° C in air. The decoloration rates monitored by the absorption intensity of the MB solution indicated that the composite thin films of Ag with an amount less than 40 mol% are not effective under vis-irradiation, though they can work as a photocatalyst under UV-irradiation. Further, the UV-sensitivity of the composite thin films gradually decreased to almost half the level of that of the TiO2 thin film fabricated under the identical conditions when the Ag amount increased from 10 to 40 mol%. Contrarily, the composite thin films of Ag content larger than 50 mol% showed the vis-responsive activity, whose level was slightly lower than the decreased UV-sensitivity. Diffuse reflectance spectra suggested that the vis-responsiveactivity of the composite thin films is due to the conductivity, localized surface plasmon resonance and surface plasmon resonance of Ag-NP. It was also elucidated that the vis-responsive level of the composite thin films corresponds to their electrical conductivity that depends on the Ag content. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is a versatile and inexpensive semiconductor with a wide direct band gap that has applicability in several scientific and technological fields. In this work, we report the synthesis of ZnO thin films via two simple and low-cost synthesis routes, i.e., the molecular precursor method (MPM) and the sol–gel method, which were deposited successfully on microscope glass substrates. The films were characterized for their structural and optical properties. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for piezoelectric applications. The surface roughness derived from atomic force microscopy (AFM) analysis indicates that films prepared via MPM were relatively rough with an average roughness (Ra) of 2.73 nm compared to those prepared via the sol–gel method (Ra = 1.55 nm). Thin films prepared via MPM were more transparent than those prepared via the sol–gel method. The optical band gap of ZnO thin films obtained via the sol–gel method was 3.25 eV, which falls within the range found by other authors. However, there was a broadening of the optical band gap (3.75 eV) in thin films derived from MPM. [ABSTRACT FROM AUTHOR]

Correction for 'A colorimetric probe for the real-time naked eye detection of cyanide and hydroxide ions in tap water: experimental and theoretical studies' by Veikko Uahengo et al., Analyst, 2019, 144, 6422–6431. [ABSTRACT FROM AUTHOR]

The Africa Capacity-Building Initiative is a Royal Society programme funded by the former UK Department for International Development to develop collaborative research between scientists in sub-Saharan Africa and the UK. Initially, four institutions were involved in the Chem4Energy consortium: Cardiff University in the UK and three African partners, the Kwame Nkrumah University of Science and Technology, Ghana, the University of Namibia and the University of Botswana, soon also including the Botswana International University of Science and Technology. The Chem4Energy research programme focused on 'New materials for a sustainable energy future: linking computation with experiment', aiming to deploy the synergy between state-of-the-art computational and experimental techniques to design and optimize new catalysts and semiconductor materials for renewable energy applications, based on materials that are abundant and readily available in African countries. The Chem4Energy consortium has achieved ambitious research goals, graduated seven PhD students and delivered a high-quality cross-disciplinary training programme in materials science and simulation techniques relevant to renewable energy applications. Since 2021, the extended consortium, including North-West University and the Centre for High-Performance Computing in South Africa, has remained active through an annual Chem4Energy conference series, with the sixth meeting taking place in Namibia in April 2025., Competing Interests: We declare we have no competing interests., (© 2024 The Author(s).)

Metal sulphides, including zinc sulphide (ZnS), are semiconductor photocatalysts that have been investigated for the photocatalytic degradation of organic pollutants as well as their activity during the hydrogen evolution reaction and water splitting. However, devising ZnS photocatalysts with a high overall quantum efficiency has been a challenge due to the rapid recombination rates of charge carriers. Various strategies, including the control of size and morphology of ZnS nanoparticles, have been proposed to overcome these drawbacks. In this work, ZnS samples with different morphologies were prepared from zinc and sulphur powders via a facile hydrothermal method by varying the amount of sodium borohydride used as a reducing agent. The structural properties of the ZnS nanoparticles were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. All-electron hybrid density functional theory calculations were employed to elucidate the effect of sulphur and zinc vacancies occurring in the bulk as well as (220) surface on the overall electronic properties and absorption of ZnS. Considerable differences in the defect level positions were observed between the bulk and surface of ZnS while the adsorption of NaBH 4 was found to be highly favourable but without any significant effect on the band gap of ZnS. The photocatalytic activity of ZnS was evaluated for the degradation of rhodamine B dye under UV irradiation and hydrogen generation from water. The ZnS nanoparticles photo-catalytically degraded Rhodamine B dye effectively, with the sample containing 0.01 mol NaBH 4 being the most efficient. The samples also showed activity for hydrogen evolution, but with less H 2 produced compared to when untreated samples of ZnS were used. These findings suggest that ZnS nanoparticles are effective photocatalysts for the degradation of rhodamine B dyes as well as the hydrogen evolution, but rapid recombination of charge carriers remains a factor that needs future optimization., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Amakali, Živković, Warwick, Jones, Dunnill, Daniel, Uahengo, Mitchell, Dzade and de Leeuw.)