Strong Visible Light Absorption Research Articles

Stearic acid-coated plasmonic Ag nanoparticles as a dual catalyst for enhanced NiO chemo and photo catalysis

The phenomenon of Localized Surface Plasmon Resonance (LSPR) in plasmonic metal nanoparticles causes a strong absorption of visible light and leads to the generation of hot electrons on the surface and the creation of localized electromagnetic fields near the surface. This characteristic enhances the catalytic performance of a plasmonic metal Ag–NiO nanocomposite (NiO-SNP) when exposed to low-flux visible light irradiation. The NiO-SNP was synthesized using a simple and cost-effective ultrasonication method. Its structural, morphological, and optical properties were analyzed, confirming the formation of nanocomposites. The proximity of stearic acid-coated Ag nanoparticles (SNP) acts as visible light-harvesting antennas, promoting NiO's activity for effectively reducing paracetamol (PM) drugs. The improved catalytic property is attributed to an electron relay effect, while the strong electromagnetic fields generated by irradiated Ag nanoparticles facilitate the concentration of PM molecules at active sites, leading to accelerated reaction rates. NiO-SNP2 demonstrates remarkable PM degradation: 97 % in tap water and 82.6 % in deionized water within 10 min, demonstrating its catalytic effectiveness. The plasmonic SNP mechanism in NiO-SNP1 nanocomposites enhances photocatalytic efficiency by up to 90 %, owing to efficient charge separation and transfer, resulting in a notable 1.5-fold increase in PM degradation. The degradation kinetics follow a pseudo-first-order model, with rate constants (k) ranging from approximately 0.059 to 0.6104 min⁻1, underscoring the crucial role of Ag nanoparticles in enhancing photocatalytic activity and degradation efficiency. Catalysis and visible light photocatalysis are significantly improved with increasing concentrations of NiO and SNP, respectively. This research could inspire a new approach to transforming traditional metal catalysis into plasmonic-metal catalysis.

Review On Strategies For the Design and Synthesis of Flower‐Like Bi2WO6 and BiOX (X=F, Cl, Br, I) Composites for Photocatalytic Environmental Remediation

AbstractIn latest events, water pollution has posed an immense threat, and its sustainable treatment is a topic of concern. Among myriad of water treatment, research community has lensed towards sustainable heterogeneous photocatalysis especially, inorganic semiconductors. Bismuth tungstate a pristine Aurivillius compound with unique crystal structure, exceptional photochemical stability, and strong redox abilities but minimum visible light absorption and quick carrier recombination are its caveats, these caveats are circumvented by synthesizing BiOX (X=F, Cl, Br and I) composites with surface modifiers, doping with hetero atoms (metals and non‐metals), construction of the heterojunction and amalgamation of carbon materials. The heart of this review is strategic engineering of flower‐like morphology photocatalyst synthesis and optical properties, it also discusses the charge transfer kinetics, photocatalytic performance, and durability. The flower‐like morphology highlighted in this review is due to its ability to harvest light, providing larger specific surface area which introduces more active sites and efficient excitons generation. The comprehensive tabulated data in this review will help the actively engaged research community in Bismuth heterogenous photocatalysis. It also sheds light on the future view of environmental remediation via photocatalytic developments.

Facile synthesis of Ag2S cocatalyst modified Zn0·6Cd0·4S for efficient photocatalytic hydrogen production

The investigation and development of straightforward methods for fabricating efficient photocatalysts are critical for converting solar energy to fuel. This study reports the successful synthesis of Ag2S/Zn0·6Cd0·4S (AZC) composites featuring zinc vacancies using a simple, two-step hydrothermal approach. These composites, characterized by nanoparticle morphologies, demonstrated strong visible light absorption, high photocurrent density and exceptional charge-transfer efficiency. Notably, the 0.5% AZC composite showcased outstanding hydrogen production (18.77 mmol g−1 h−1) and stability, achieving an apparent quantum yield (AQY) of 23.8%. The remarkable photocatalytic activity of this composite is attributed to the inclusion of Ag2S serving as an electron trapping cocatalyst, and the presence of zinc vacancies. Furthermore, the study elucidates the underlying photocatalytic mechanism of the 0.5% AZC composite.

Constructing Photocatalytic Covalent Organic Frameworks with Aliphatic Linkers.

Photocatalytic covalent organic frameworks (COFs) are typically constructed with rigid aromatic linkers for crystallinity and extended π-conjugation. However, the essential hydrophobicity of the aromatic backbone can limit their performances in water-based photocatalytic reactions. Here, we for the first time report the synthesis of hydrophilic COFs with aliphatic linkers [tartaric acid dihydrazide (TAH) and butanedioic acid dihydrazide] that can function as efficient photocatalysts for H2O2 and H2 evolution. In these hydrophilic aliphatic linkers, the specific multiple hydrogen bonding networks not only enhance crystallization but also ensure an ideal compatibility of crystallinity, hydrophilicity, and light harvesting. The resulting aliphatic linker COFs adopt an unusual ABC stacking, giving rise to approximately 0.6 nm nanopores with an improved interaction with water guests. Remarkably, both aliphatic linker-based COFs show strong visible light absorption, along with a narrow optical band gap of ∼1.9 eV. The H2O2 evolution rate for TAH-COF reaches up to 6003 μmol h-1 g-1, in the absence of sacrificial agents, surpassing the performance of all previously reported COF-based photocatalysts. Theoretical calculations reveal that the TAH linker can enhance the indirect two-electron oxygen reduction reaction for H2O2 production by improving the O2 adsorption and stabilizing the *OOH intermediate. This study opens a new avenue for constructing semiconducting COFs using nonaromatic linkers.

Selective Photocatalytic CO2 Reduction Through Plasmonic Z‐Scheme Ag‐Bi2O3‐ZnO Heterostructures

AbstractCombination of plasmonic noble metal with semiconductors offers a promising and potential solar energy harvesting and conversion route. Herein, plasmonic Z‐scheme Ag‐Bi2O3‐ZnO (AgBZ) heterostructure is designed and synthesized via solution combustion and photo‐deposition method. Metallic Ag nanoparticles (NPs) were deposited over Bi2O3‐ZnO heterostructure; thus, they exhibit strong visible light absorption owing to surface plasmon resonance (SPR). The photocatalytic efficiency of the synthesized catalysts is investigated by the photocatalytic CO2 reduction to fuels under simulated solar light irradiation. The present system has shown an outstanding photocatalytic CO2 reduction and excellent selectivity of CO. The evolved rate of CO fuel, the amount of CO produced per unit time, over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was (96.74 μmol g−1/h) which was approximately 12 times larger than that of Bi2O3‐ZnO (0AgBZ) and 49‐fold than the quantity of evolved CO fuels over pure ZnO photocatalyst. The percentage of evolved CO to CH4 fuels over optimized Ag‐Bi2O3‐ZnO (3AgBZ) heterostructures was about 50 : 1compared to that of 2 : 3 over Bi2O3‐ZnO (0AgBZ). The great improvement and the high selectivity would be ascribed to the synergistic effect of metallic surface plasmon resonance and the Z‐scheme charges transfer system. This work would open a window to construct a single photocatalyst with different charge separation systems and excellent CO2 reduction selectivity. Finally, the mechanism for the enhanced photocatalytic performance by the synergistic effect was described and discussed.

Exploring the ferroelectric photocatalytic potential of R3c-structured InVO3: A computational study

Ferroelectric oxides with large band gaps or band edge positions that are difficult to cross the water oxidation-reduction potential are not conducive to photocatalytic hydrogen production. This study systematically investigates the potential application of R3c-structured InVO3 in the field of photocatalysis through density functional theory calculations. The mechanical and phonon frequency stability of InVO3 is verified through stability analysis, followed by the confirmation of its excellent ferroelectric properties through first-principles calculations. The calculated optical properties of InVO3 are explored to reveal its strong absorption of visible light and high photoelectric conversion efficiency. InVO3 exhibits excellent charge carrier transport properties through calculations of electron mobility, promising efficient energy conversion in photocatalytic water splitting. The band edge positions of InVO3 can cross the water oxidation-reduction potential, providing theoretical support for its application in the field of photocatalysis. R3c-structured InVO3 is a potential high-performance ferroelectric photocatalytic material.

Decisive role of preparation technique on the structural, electrical and magnetic properties of vanadium doped ZnO nanoparticles

1% vanadium doped ZnO powders have been successfully synthesized via two different preparation techniques viz., glycine assisted combustion method and mechanical attrition method to understand their impact on the structure-property relation. X-ray Diffraction study validates the Wurtzite phase formation of ZnO with hexagonal structure. X-ray diffraction peak discloses the marked role of size and strain component. Evidently, the shift of lattice strain with the preparation techniques from compressive to tensile nature show the importance of structure property relations in the ZnO compounds. SEM micrographs depict the formation of densely populated nanograins with networking like structures which is characteristics of combustion synthesized product whereas as top down approach exhibits the presence of coarse grains amidst the broken sea of fine particles. Selected area electron diffraction (SAED) images display ring and bright circular spot pattern with changes in method of preparation, which further clarifies the distinct nature of investigated ZnO:V particles. Vibrational spectral study gives clear evidence on the structural disorder as deduced from the changes associated with longitudinal optical mode phonon scattering. Interestingly, the UV spectral study divulges the increment in optical band gap as well as a strong visible light absorption (about 30 %) for milled ZnO:V over their chemically prepared counterparts. Photoluminescence spectra of milled V doped ZnO upheld the structural disorder taken place with the suppression of Near Band Edge (NBE) transition and the shifting of broad asymmetric defect emission band towards the lower wavelength regime. Impedance study enlightens the crucial role of synthesis method with 5 times enhanced grain boundary resistance along with suppression of grain contribution in the milled samples. Magnetic study highlights the remarkable distinction of preparation route which alters the ferromagnetic ordering in the combustion synthesized samples to conventional diamagnetic signature of the host ZnO in the milled samples.

The Critical Role of Anharmonic Lattice Dynamics for Macroscopic Properties of the Visible Light Absorbing Nitride Semiconductor CuTaN2

AbstractTernary nitride semiconductors are rapidly emerging as a promising class of materials for energy conversion applications, offering an appealing combination of strong light absorption in the visible range, desirable charge transport characteristics, and good chemical stability. In this work, it is shown that finite‐temperature lattice dynamics in CuTaN2 – a prototypical ternary nitride displaying particularly strong visible light absorption – exhibit a pronounced anharmonic character that plays an essential role in defining its macroscopic optoelectronic and thermal properties. Low‐frequency vibrational modes that are Raman‐inactive from symmetry considerations of the average crystal structure and unstable in harmonic phonon calculations are found to appear as intensive Raman features near room temperature. The atomic contributions to the anharmonic vibrations are characterized by combining Raman measurements with molecular dynamics and density functional theory calculations. This analysis reveals that anharmonic lattice dynamics have large ramifications on the fundamental properties of this compound, resulting in uniaxial negative thermal expansion and the opening of its bandgap to a near‐optimal value for solar energy harvesting. The atomic‐level understanding of anharmonic lattice dynamics, as well as the finding that they strongly influence key properties of this semiconductor at room temperature, have important implications for design of new functional materials, especially within the emerging class of ternary nitride semiconductors.

NOx degradation by cement mortar containing B-TiO2/MgAl-CLDH under visible light: Experimental and modeling

In this paper, an advanced photocatalyst, B-TiO2/MgAl-CLDH, was synthesized and applied in cement mortar. The photocatalytic NOx degradation ability of cement mortar containing B-TiO2/MgAl-CLDH under different initial NOx concentrations and flow rates was investigated. The results show that B-TiO2/MgAl-CLDH has stronger visible light absorption, lower recombination rate of electron-hole pairs and narrower optical band gap than commercial nano-TiO2 (P25), resulting in enhanced NOx removal efficiency. Specifically, the maximum NOx degradation ratio of B-TiO2/MgAl-CLDH is 23.4% within 30 min, which is about 5 times that of P25. For photocatalytic mortar, the initial NOx concentration (from 1.0 ppm to 2.0 ppm) and flow rate (from 1 L/min to 3 L/min) were positively correlated with NOx removal amount, while negatively correlated with NOx removal ratio. Based on the internal molecular diffusion properties of NOx, Langmuir-Hinshelwood and the power law kinetic models were used to predict the NOx degradation ability of photocatalytic mortar. The modeling of NOx degradation process presents a reliable prediction of the NOx removal ability of photocatalytic mortar, serving as a valuable tool for assessing the mortar’s NOx removal effectiveness for policymakers and engineers.

Revealing the lattice engineering of Delafossite in core–shell CuRhO2@CuGaO2 heterostructure for efficient visible light photocatalytic activity

The establishment of heterojunctions at phase interfaces represents a pivotal strategy for enhancing photocatalytic performance. However, the inferior interfacial contact caused by the mismatch of crystal structure or lattice parameters seriously hampers the rapid and smooth migration of charge carriers in traditional heterojunctions. In this work, a tightly integrated Delafossite-based core–shell CuRhO2@CuGaO2 heterojunction was judiciously designed and constructed via a hydrothermal approach. Experimental and density-functional theory calculation results co-unravel that the built-in electric field is established in the lattice-matched heterogeneous interfaces, thereby providing smooth interface charge separation and transfer via the Z-scheme pathways. Benefitting from the heterojunction effect and unique core–shell coupling architecture, the strong visible light absorption and fast spatial charge transfer are realized in the CuRhO2@CuGaO2 heterostructure. The photocurrent density of the CuRhO2@CuGaO2 heterojunction is nearly 1.25 and 3.75 times those of pristine CuRhO2 and CuGaO2, respectively. As a result, the CuRhO2@CuGaO2 heterostructure reveals an excellent photocatalytic degradation rate of tetracycline hydrochloride, achieving a 3.02 and 2.38-fold improvement than those of the CuRhO2 and CuGaO2, respectively. This work is expected to pave the way for novel insights into the design of efficient heterojunction photocatalysts to steer the rapid photocarrier flows across the heterointerface.

Construction of a photo-assisted peroxymonosulfate activation system comprised of iron phthalocyanine/O-doped carbon nitride for efficient tetracycline removal

The integration of peroxymonosulfate (PMS) activation and photocatalysis is an effective advanced oxidation technology for the degradation of water pollutants. In this study, iron phthalocyanine (FePc) is successfully loaded onto O-doped porous carbon nitride (OCN) forming a catalyst working in photo-assisted PMS activation. OCN is a metal-free light absorber with strong visible light absorption, while FePc could serve as a photosensitizer and PMS activator. At the same time, the construction of FePc/OCN heterojunction can form the strong internal electric field for charge migration between FePc and OCN. As a result, complete tetracycline (TC) removal within 30 min can be achieved over optimal FePc/OCN catalyst in the presence of light and PMS. Systematic controlled experiments were also carried out to reveal the effect of pH, anion, and aqueous matrix. Cyclic stability test and Fe leaching experiments indicate that the synthesized FePc/OCN is relatively stable and shows the potential in practical application. Furthermore, a comprehensive investigation was conducted on the reactive species generated during the reaction process as well as the degradation pathways of the target pollutants. This work aims to provide new insights into the design of efficient catalysts for photo-assisted PMS activation.

COF/In2S3 S-Scheme Photocatalyst with Enhanced Light Absorption and H2O2-Production Activity and fs-TA Investigation.

Photocatalytic hydrogen peroxide (H2O2) synthesis from water and O2 is an economical, eco-friendly, and sustainable route for H2O2 production. However, single-component photocatalysts are subjected to limited light-harvesting range, fast carrier recombination, and weak redox power. To promote photogenerated carrier separation and enhance redox abilities, an organic/inorganic S-scheme photocatalyst is fabricated by in situ growing In2S3 nanosheets on a covalent organic framwork (COF) substrate for efficient H2O2 production in pure water. Interestingly, compared to unitary COF and In2S3, the COF/In2S3 S-scheme photocatalysts exhibit significantly larger light-harvesting range and stronger visible-light absorption. Partial density of state calculation, X-ray photoelectron spectroscopy, and femtosecond transient absorption spectroscopy reveal that the coordination between In2S3 and COF induces the formation of mid-gap hybrid energy levels, leading to smaller energy gaps and broadened absorption. Combining electron spin resonance spectroscopy, radical-trapping experiments, and isotope labeling experiments, three pathways for H2O2 formation are identified. Benefited from expanded light-absorption range, enhanced carrier separation, strong redox power, and multichannel H2O2 formation, the optimal composite shows an impressive H2O2-production rate of 5713.2µmol g-1 h-1 in pure water. This work exemplifies an effective strategy to ameliorate COF-based photocatalysts by building S-scheme heterojunctions and provides molecular-level insights into their impact on energy level modulation.

DFT evaluation the photo-catalytic performance of g-C3N4 dots/ZnO with O/S doping

To develop the high-performance g-C3N4-based photo-catalysts and understand the mechanism of photo-catalytic degradation of volatile organic compounds (VOCs), we evaluated the photo-catalytic performance and corresponding catalytic mechanisms of g-C3N4 dots/ZnO (CNZO) systems using density functional theory (DFT) calculations. Our results showed that the combination of g-C3N4 dots and ZnO monolayer has a appropriate band gap and strong visible light absorption, significantly enhancing photoelectron excitation and immigration. We also observed that O/S doping exerted a significant impact on the band structure and interfacial coupling, thereby increasing the number of photoelectrons that move from the valence band (VB) of ZnO monolayer to the conduction band (CB) of g-C3N4 dots, thereby enhancing the separation of photo-generated electron-hole pairs in O/S-CNZO. Furthermore, the suitable CB and VB positions of O/S-CNZO encourage the adsorption of surface H2O and O2 molecules, leading to the generation of ·OH and ·O2− radicals crucial in VOCs degradation. This work introduces new approaches and perspectives for constructing novel photo-catalysts. Additionally, it involves a theoretical evaluation of the photo-catalytic performance of O/S-CNZO.

Photostability and visible-light-driven photoactivity enhancement of hierarchical C@ZnCdS/ZnS/MoS2

Zinc cadmium sulfide solid (Zn x Cd1−x S) related composites received great attention in photocatalytic hydrogen production because of their tunable bandgap and strong visible light absorption range. But sulfide-based metal materials commonly suffer from photo-corrosion issues. It is very important to construct the photocatalysts with high efficient activity and photostability for H2 production. Herein, we successively prepared ZnCdS/ZnS (ZCS/ZS) heterostructures, ZnCdS/ZnS/MoS2 (ZCS/ZS/M) heterostructures decorated ZCS/ZS with MoS2 quantum dots, then we obtained x-C@ZCS/ZS and x-C@ZCS/ZS/M heterostructures encapsulated ZCS/ZS and ZCS/ZS/M with carbon layer. The performance of the photocatalytic hydrogen production showed that sample 0.05-C@ZCS/ZS/M has a remarkable photocatalytic H2 evolution rate of 15.231 mmol·h−1·g−1 with noble metal-free co-catalysts. This rate was approximately 21 times higher than that of the pristine ZCS/ZS photocatalyst. The optimized sample reveals an excellent stability, without activity losses after 10 h. The improved photocatalytic activity can be attributed to the unique heterojunction structure formed by ZCS/ZS and MoS2. Additionally, the carbon films played a crucial role in providing excellent stability by spatially separating the sites for redox reactions, thereby inhibiting the recombination of photo-generated electron–hole pairs.

Ligand-Induced Synthesis of Highly Stable NM88(DB)@COF-JLU19 Composite: Accelerating Electron Flow for Visible-Light-Efficient Degradation of Tetracycline Hydrochloride.

In recent years, the response of new porous materials to visible light and their potential applications in wastewater treatment has received extensive attention from the scientific community. Metal Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) have been the focus of attention due to their strong visible light absorption, high specific surface area, well-regulated pore structures, and diverse topologies. In this study, a novel MOF@COF composite with a high surface area, high crystallinity, and structural stability was obtained using the covalent bond formation strategy from COF-JLU19 and NH2-MIL-88B(Fe). Under visible light irradiation, the degradation of tetracycline hydrochloride by this material reached more than 90% within 10 min and was completely degraded within 30 min, which exceeded the degradation rate of individual materials. Remarkably, the catalytic activity decreased by less than 5% even after five degradation cycles, indicating good structural stability. The excellent photocatalytic performance of the NM88(DB)@COF-JLU19 hybrids was attributed to the formation of covalent bonds, which formed a non-homogeneous interface that facilitated effective charge separation and promoted the generation of hydroxyl radicals.

Porphyrin-Polyoxotungstate Molecular Hybrid as a Highly Efficient, Durable, Visible-Light-Responsive Photocatalyst for Aerobic Oxidation Reactions.

Organic-polyoxometalate (POM) hybrids have recently attracted considerable interest because of their distinctive properties and wide-ranging applications. For the construction of organic-POM hybrids, porphyrins are promising building units owing to their optical properties and reactivity, including strong visible-light absorption and subsequent singlet-oxygen (1O2*) generation. However, the practical utilization of porphyrins as photocatalysts and photosensitizers is often hindered by their own degradation by 1O2*. Therefore, there is a substantial demand for the development of porphyrin-derived photocatalysts with both high efficiency and durability. Herein, we present a porphyrin-polyoxotungstate molecular hybrid featuring a face-to-face stacked porphyrin dimer (I) fastened by four lacunary polyoxotungstates. Hybrid I exhibited remarkable efficiency and durability in photocatalytic aerobic oxidation reactions, and the selective oxidation of various dienes, alkenes, sulfides, and amines proceeded using just 0.003 mol % of the catalyst. Mechanistic investigations suggested that the high activity of I stems from the efficient generation of 1O2*, resulting from the heavy-atom effect of POMs. Furthermore, despite its high efficiency in 1O2* generation compared to free porphyrins, I exhibited superior durability against 1O2*-induced degradation under photoirradiation.

Embedding In2.77S4 into NCDs-(g-C3N5) hybrid materials to enhance photocatalytic hydrogen production and rhodamine B degradation by constructing electron-highways

We propose a potential solution to the problem of severe recombination of photogenerated electron-hole pairs in composite catalysts. The g-C3N5 has better electronic properties and photocatalytic efficiency than g-C3N4, and In2.77S4 is a typically sulfur-deficient sulfide with stable structure and strong visible light absorption. However, the In2.77S4/g-C3N5 composite catalyst has severe recombination of photogenerated electron-hole pairs, which limits its performance. To solve this problem, we introduced NCDs (nitrogen-doped carbon dots) into g-C3N5 to prepare hybrid material, which subsequently combined with In2.77S4. The high-efficiency S-scheme In2.77S4/NCDs-(g-C3N5) heterojunction was prepared by electrostatic self-assembly to prevent the thermal decomposition of g-C3N5. Photocatalytic experiments show that In2.77S4/NCDs-(g-C3N5) composite has excellent photodegradation efficiency of rhodamine B (94.23 %), high photocatalytic H2 production (7134 μmol·g−1h−1), and good reusability in the visible light. The H2 evolution rate of In2.77S4/NCDs-(g-C3N5) composite is about 30.10, 3.89 and 3.08 folds than In2.77S4, g-C3N5 and In2.77S4/g-C3N5, respectively. The photoluminescence spectroscopy (PL) and the time-resolved fluorescence decay (TRF) indicated a substantial reduction in photogenerated carrier recombination of In2.77S4/NCDs-(g-C3N5) compared to In2.77S4/g-C3N5. Taking advantage of the high conductivity of NCDs, the electron-highways were constructed in heterojunctions, which accelerates the interfacial depletion of useless electron-hole pairs and reserved more strong redox carriers. In addition, we inferred a possible energy band structure for In2.77S4/NCDs-(g-C3N5) heterojunction based on the energy band bending theory. This work provides an expandable idea for improving the utilization efficiency of photogenerated carriers by constructing electron-highways in heterojunctions.

Visible-light absorption of indium oxide thin films via Bi3+ doping for visible-light-responsive photocatalysis

In2O3 is commonly used as a photocatalyst for hydrogen energy storage. However, it has the disadvantage of a large optical bandgap (3.7 eV), resulting in low absorption of visible light, which corresponds to 50 % of sunlight energy. Band engineering is an efficient method to add visible-light responsivity to wide-bandgap In2O3. In this study, the band engineering of In2O3 was performed by incorporating bismuth to obtain an intermediate band that could absorb visible light. Thin films of In2O3 doped with bismuth (IBO) were grown using mist chemical vapor deposition (CVD), and their optical properties were investigated. Transmittance measurements showed that the IBO thin film exhibited absorption in the visible light region of 400–700 nm, indicating that the introduction of bismuth created an intermediate band in the bandgap of In2O3. IBO thin films with platinum as a co-catalyst could almost completely degrade methylene blue under visible light (420 nm) irradiation for 72 h. Thus, the incorporation of bismuth into In2O3 via mist CVD and the strong absorption of visible light owing to its intermediate band were demonstrated. This study demonstrates that IBO thin films with large absorption in the visible-light region are promising materials for visible-light-responsive photocatalysts.

Oxidation-state sensitive light-induced dynamics of Ruthenium-4H-Imidazole complexes.

Oxidized molecular states are key intermediates in photo-induced redox reactions, e. g., intermolecular charge transfer between photosensitizer and catalyst in photoredox catalysis. The stability and longevity of the oxidized photosensitizer is an important factor in optimizing the respective light-driven reaction pathways. In this work the oxidized states of ruthenium(II)-4H-imidazole dyes are studied. The ruthenium complexes constitute benchmark photosensitizers in solar energy interconversion processes with exceptional chemical stability, strong visible light absorption, and favourable redox properties. To rationalize the light-induced reaction in the oxidized ruthenium(III) systems, we combine UV-vis absorption, resonance Raman, and transient absorption spectroelectrochemistry (SEC) with time-dependent density functional theory (TDDFT) calculations. Three complexes are compared, which vary with respect to their coordination environment, i. e., combining an 4H-imidazole with either 2,2'-bipyridine (bpy) or 2,2';6'2"-terpyridine (tpy) coligands, and chloride or isothiocyanate ligands. While all oxidized complexes have similar steady state absorption properties, their excited state kinetics differ significantly; the study thus opens the doorway to study the light-driven reactivity of oxidized molecular intermediates in intermolecular charge transfer cascades.

Identification of Crucial Photosensitizing Factors to Promote CO2 -to-CO Conversion.

The sensitizing ability of a catalytic system is closely related to the visible-light absorption ability, excited-state lifetime, redox potential, and electron-transfer rate of photosensitizers (PSs), however it remains a great challenge to concurrently mediate these factors to boost CO2 photoreduction. Herein, a series of Ir(III)-based PSs (Ir-1-Ir-6) were prepared as molecular platforms to understand the interplay of these factors and identify the primary factors for efficient CO2 photoreduction. Among them, less efficient visible-light absorption capacity results in lower CO yields of Ir-1, Ir-2 or Ir-4. Ir-3 shows the most efficient photocatalytic activity among these mononuclear PSs due to some comprehensive parameters. Although the Kobs of Ir-3 is ≈10 times higher than that of Ir-5, the CO yield of Ir-3 is slightly higher than that of Ir-5 due to the compensation of Ir-5's strong visible-light-absorbing ability. Ir-6 exhibits excellent photocatalytic performance due to the strong visible-light absorption ability, comparable thermodynamic driving force, and electron transfer rate among these PSs. Remarkably, the CO2 photoreduction to CO with Ir-6 can achieve 91.5 μmol, over 54 times higher than Ir-1, and the optimized TONC-1 can reach up to 28160. Various photophysical properties of the PSs were concurrently adjusted by fine ligand modification to promote CO2 photoreduction.