Hole Transfer Research Articles

Design of new CoFe2O4/MXene/NaTaO3 double heterostructures for efficient photodegradation of antibiotic

Facilitating the dissociation and transfer of light-excited electrons and holes in semiconductors is crucially important for enhancing their photocatalytic activities and promoting their photocatalytic application in pollutant elimination. In this study, we have immobilized Ti3C2 (TC) nanoparticles (derived from TC MXene) as well as CoFe2O4 (CFO) nanoparticles on the surface of NaTaO3 (NTO) cubes to construct new CFO/TC/NTO double heterostructure photocatalysts. A series of experiments combined with theoretical calculations evidence the formation of interface electric fields at the TC/NTO and CFO/NTO heterojunction interfaces and efficient photocarrier dissociation/transfer behavior. Simulated-sunlight-driven photodegradation of ciprofoxacin (CIP) demonstrates a significantly enhanced photocatalysis of the heterostructured photocatalysts; particularly, the 40CFO/20TC/NTO, photodegrading 97.7 % of CIP within 60 min, exhibits a photodegradation performance that is enhanced by 3.2 (or 3.5) times over that of bare NTO (or CFO). The interface-field-facilitated dissociation/transfer of photocarriers is the crucial mechanism for the heterostructure-enhanced photocatalysis. Additionally, the photodegradation processes of CIP and potential toxicities of the intermediate products were elucidated. The present study supplies researchers with a significant guidance for designing excellent heterostructured photocatalysts.

Accelerating Small Electron Polaron Dissociation and Hole Transfer at Solid-Liquid Interface for Enhanced Heterogeneous Photoreaction.

In a photocatalysis process, quick charge recombination induced by small electron polarons in a photocatalyst and sluggish kinetics of hole transfer at the solid-liquid interface have greatly limited photocatalytic efficiency. Herein, we demonstrate hydrated transition metal ions as mediators that can simultaneously accelerate small electron polaron dissociation (via metal ion reduction) and hole transfer (through high-valence metal production) at the solid-liquid interface for improved photocatalytic pollutant degradation. Fe3+, by virtue of its excellent redox ability as a homogeneous mediator, enables the BiVO4 photocatalyst to achieve drastically increased photocatalytic degradation performance, up to 684 times that without Fe3+. The enhanced performance results from Fe(IV) species production (via Fe3+ oxidation) induced by dissociation of small electron polarons (via Fe3+ reduction), featuring an extremely low kinetic barrier (5.4 kJ mol-1) for oxygen atom transfer thanks to the donor-acceptor orbital interaction between Fe(IV) and organic pollutants. This work constructs a high-efficiency artificial photosynthetic system through synergistically eliminating electron localization and breaking hole transfer limitation at the solid-liquid interface for constructing high-efficiency artificial photosynthetic systems.

Development of Semi-Empirical and Machine Learning Models for Photoelectrochemical Cells

We introduce a theoretical model for the photocurrent-voltage (I-V) characteristics designed to elucidate the interfacial phenomena in photoelectrochemical cells (PECs). This model investigates the sources of voltage losses and the distribution of photocurrent across the semiconductor–electrolyte interface (SEI). It calculates the whole exchange current parameter to derive cell polarization data at the SEI and visualizes the potential drop across n-type cells. The I-V model’s simulation outcomes are utilized to distinguish between the impacts of bulk recombination and space charge region (SCR) recombination within semiconductor cells. Furthermore, we develop an advanced deep neural network model to analyze the electron–hole transfer dynamics using the I-V characteristic curve. The model’s robustness is evaluated and validated with real-time experimental data, demonstrating a high degree of concordance with observed results.

Sublimation and Recrystallization of CsPbBr3 Constructing a Perovskite-Carbon Interface to Facilitate Hole Transfer in Printable All-Inorganic Perovskite Solar Cells.

All-inorganic perovskite solar cells (APSCs) are a promising photovoltaic technology due to their unique physical and optical properties. For printable all-inorganic perovskite solar cells, the key factors limiting their photoelectric conversion performance are the crystallization of perovskite and the hole collection capability at the perovskite-carbon interface. In this study, leveraging the high-temperature tolerance of CsPbBr3 perovskite, the sublimation and recrystallization processes were controlled, significantly improving the crystalline quality of the perovskite and suppressing the generation of the nonphotovoltaic CsPb2Br5 phase. Furthermore, a continuous distribution of high-quality CsPbBr3 crystals was achieved at the interface between the carbon electrode and the zirconium oxide layer, ensuring efficient collection of photogenerated holes. The photoelectric conversion efficiency of the printable mesoscopic all-inorganic perovskite solar cell was increased from 5.04 to 8.34% (with a record value of 10.04%) and achieved an ultrahigh open-circuit voltage of 1.54 V due to the significant improvement in the crystal quality of CsPbBr3. This study proposes a novel strategy to enhance the photovoltaic conversion performance of carbon-based all-inorganic perovskite solar cells by suppressing the presence of nonphotovoltaic phases.

Regulating Electron‐Phonon Coupling by Solid Additive for Efficient Organic Solar Cells

AbstractStrong electron‐phonon coupling can hinder exciton transport and induce undesirable non‐radiative recombination, resulting in a shortened exciton diffusion distance and constrained exciton dissociation in organic solar cells (OSCs). Therefore, suppressing electron‐phonon coupling is crucially important for achieveing high‐performance OSCs. Here, we employ the solid additive to regulating electron‐phonon coupling in OSCs. The planar configuration of SA1 confers a significant advantage in suppressing lattice vibrations in the active layers, reducing the scattering of excitons by phonons. Consequently, a slow but sustained hole transfer process is identified in the SA1‐assisted film, indicating an enhancement in hole transfer efficiency. Prolonged exciton diffusion length and exciton lifetime are achieved in the blend film processed with SA1, attributed to a low non‐radiative recombination rate and low energetic disorder for charge carrier transport. As a result, a high efficiency of 20 % was achieved for ternary device with a remarkable short‐circuit current. This work highlights the important role of suppressing electron‐phonon coupling in improving the photovoltaic performance of OSCs.

Modification of solar energy and photoelectrochemical water splitting properties: using FTO/Er-TiO2/MAPbI3/CuPc/Au as modified photoelectrode

In the past decades, converting solar energy into hydrogen through photoelectrochemical water splitting has been attracted. Here, we designed a new FTO/Er-TiO2/MAPbI3/CuPc/Au photoanode with n-i-p structure for using in solar water splitting. Accourding to obtained PEC results, the FTO/Er-TiO2/MAPbI3/CuPc/Au photoanode has a photocurrent density of ∼9.8 mA cm−2 ( under a visible lamp with intensity of 100 mW cm−2 irradiation) compared to FTO/Er-TiO2/Au and FTO/Er-TiO2/MAPbI3/Au photoanodes with photocurrent density of 0.7 and 6.12 mA cm−2, respectively. This important enhancement is refered to the light absorption feature of Er-TiO2/MAPbI3 and a fast electron and hole transfer process in the Er-TiO2 and CuPc, respectively. The photoelectrochemical action of the photoelectrode is increased using erbium doping due to creation of oxygen vacancies and titanium (III) ions. Furthermore, in this research, we studided the power conversion efficiency (PCE) of FTO/Er-TiO2/MAPbI3/Au and FTO/Er-TiO2/MAPbI3/CuPc/Au solar cells. The results shown that the significant enhancement in photovoltaic properties can be observed by utilizing spin-coated CuPc nanoparticles (as hole transport layer) at least by 1.39% compared to the FTO/Er-TiO2/MAPbI3 perovskite solar cell.

Unveiling the Influence of Lower‐Valence Ni in Hydroxide Co‐Catalyst and Attaining Efficient Photoanodes with FeOOH Holes Transfer Layer for Photoelectrochemical Water Splitting

AbstractElectronic structure regulation is a prevailing approach to modifying the electrocatalysts in the oxygen evolution reaction (OER), yet its impact on the co‐catalysts modified photoanodes remains uncertain. Herein, B‐modified NiFe‐LDH (NiFeB‐hydx) co‐catalyst in situ is immobilized onto Ti‐Fe2O3 and emphasizes the effect of lower‐valence Ni (Ni2‐δ) in the photoelectrochemical (PEC) process. A flexible adjustment in the oxidation state of Ni from +2 to 0 by manipulating the Ni content and the corresponding B quantity is achieved. Interestingly, the Ni0 significantly reduces the onset potential low to 0.53 VRHE, albeit leading to wasted holes due to incomplete redox transition. An optimal amount of Ni2‐δ effectively facilitates the redox transition of Ni and achieves a delicate balance between hole extraction and consumption, substantially enhancing the PEC performance. Density functional theory calculations verifies the electron enrichment of Ni and the corresponding benefits for enhancing OER. Furthermore, introducing FeOOH as a hole transfer layer on Ti‐Fe2O3 induces a pronounced band bending effect, remarkably promoting the meticulously engineered NiFeB‐hydx/FeOOH/Ti‐Fe2O3 photoanode to a photocurrent density of 3.29 mA cm−2 at 1.23 VRHE. NiFeB‐hydx/FeOOH can be universally applied to the BiVO4 photoanode, resulting in doubled photocurrent density (4.8 mA cm−2 at 1.23 VRHE).

Electronic and photocatalytic properties of Cu4 cluster-modified Ag/g-C3N4 single-atom catalysts: A hybrid DFT study

Increasing the active sites on the catalyst surface has been a key goal to increase the catalyst efficiency. This paper presents an efficient conversion of solar energy into chemical energy, realized by a Cu4 cluster-assisted single-atom catalyst (Ag-doped g-C3N4). The catalyst enhances charge transfer and light absorption, and the unique advantages of this approach in the field of photocatalysis are substantiated by density functional theory. Under the synergistic effect of Cu4 clusters, the electronic state density distribution of the Ag single-atom catalyst substrate is drastically altered, which realizes the increase of substrate active sites and rapid charge separation and transfer. Compared with the pristine substrate g-C3N4, the new electronic state distribution and the generation of impurity energy levels lead to the narrowing of the band gap from 2.77 to 1.83 eV, accelerating the transfer and separation of electrons and holes, and enlarging the visible light absorption range from 410 to 760 nm, thus improving the solar energy utilization. Despite the reduced band gap, the conduction and valance band edges of (Ag, Cu4) codoped g-C3N4 still have sufficient potential to split water. Therefore, to improve the photocatalytic performance under visible light, simultaneous codoping of the Ag single atom and Cu4 cluster on g-C3N4 is an effective strategy. The study provides theoretical support for further optimization of single-atom catalysts.

Stretching vibration driven adiabatic transfer kinetics for photoexcited hole transfer from semiconductor to adsorbate

Interfacial hole transfer from a photoexcited semiconductor to surface adsorbates is pivotal for initiating solar-to-chemical energy conversion, yet the atomic-level transfer kinetics remains elusive. Using the methoxy/TiO2(110) system as an archetype, here we elucidate the hole transfer mechanism from hole-trapping lattice oxygen to the methoxy adsorbate at gas/solid and liquid/solid interfaces through molecular dynamics simulations and static minimum energy path calculations. Instead of direct nonadiabatic hopping, we uncover an adiabatic migration pathway adapted to local substrate relaxation, driven by a bond-stretching mechanism supported by stronger Ti-O stretching vibrations. Notably, this mechanism persists at the aqueous methoxy/TiO2(110) interface, albeit hindered by interfacial water and coadsorbates. Surprisingly, the hole transfer barriers across various photoexcited adsorbate/TiO2 interfaces correlate more closely with the vertical excitation energies of the adsorbates rather than their redox potentials, indicating an early-type transition-state nature. These insights deepen our understanding of elementary hole transfer kinetics in surface photochemistry.

Phase Distribution Dictates Charge Transfer and Transport Dynamics in Layered Quasi-2D Perovskite.

Strategic manipulation of spatiotemporal evolution of charge carriers is critical for optimizing performance of quasi-two-dimensional (2D) perovskite-based optoelectronic devices. Nonetheless, the inhomogeneous phase distribution and band alignment engender intricate energy landscapes, complicating internal charge and energy funneling processes. Herein, we integrate high spatiotemporal resolution transient absorption microscopy with multiple time-resolved spectroscopy and find that asynchronous electron and hole transfers rather than direct energy transfer govern the funneling mechanisms. Notably, the charge funneling pathways and transport behaviors can be modifiable by phase manipulation. The accumulation of small-n phases suppresses the electron funneling toward large-n phases and doubles the carrier diffusion rate from 0.085 to 0.20 cm2/s, yielding a 1.5-fold enhancement in diffusion length. Phase order engineering is further corroborated for facilitating charge separation. Our investigation underscores the prospects of manipulating the phase distribution to control internal charge funneling and transport, thereby substantiating the theoretical foundations for optimizing optoelectronic devices.

Eco-friendly synthesis of CuO/Bi2O3 nanocomposite for efficient photocatalytic degradation of rhodamine B dye.

Plant-mediated synthesized materials are receiving more attention than conventional ones due to their wide availability, ease of access, simple preparation methods, environmental benign, and possess superior physicochemical properties. In this work, plant extract-mediated CuO, Bi2O3, and CuO/Bi2O3 nanocomposite samples were successfully synthesized using bamboo leaves extract as a capping agent. These materials were utilized for the photodegradation of Rhodamine B (RhB) dye, which served as a model organic dye pollutant. The physicochemical characterization techniques such as XRD, SEM-EDS, FTIR, and DRS-UV-vis spectrophotometry provide insight into the crystal structure, morphology, surface functional groups, and optical properties. These analyses confirm the effective formation of CuO, Bi2O3, and CuO/Bi2O3 materials. Surprisingly, upon calcination at 450°C for 4h, the color of the nanocomposite changed from pale green to gray greenish, providing evidence for the formation of the CuO in CuO/Bi2O3 nanocomposite. The photocatalytic optimization parameters such as pH (4), catalyst load (35mg), irradiation time (180min) and concentration of RhB (10 mg L-1) dye were investigated. By coupling CuO with Bi2O3 nanoparticles resulted in an improved photocatalytic property for the degradation of RhB dye under optimal conditions. As a result, CuO/Bi2O3 nanocomposite exhibited a significantly boosted photocatalytic degradation efficiency (95.6%) compared to pure CuO (40.2%) and Bi2O3 (80.5%) photocatalysts, with good reusability. For comparison purpose, the photocatalytic degradation of RhB dye using selected photocatalyst was evaluated under dark and sunlight systems. This eco-friendly approach holds great potential for synthesis new nanocomposite with modified properties, thereby enabling the practical application of high-efficiency photocatalysts. The plausible mechanism of the electrons and holes transfer was proposed.

An Efficient Algorithm for Constrained CASSCF(1,2) and CASSCF(3,2) Simulations as Relevant to Electron and Hole Transfer Problems.

We propose an efficient algorithm for the recently published electron/hole-transfer Dynamical-weighted State-averaged Constrained CASSCF (eDSC/hDSC) method studying charge transfer states and D1-D0 crossings for systems with odd numbers of electrons. By separating the constrained minimization problem into an unconstrained self-consistent-field (SCF) problem and a constrained nonself-consistent-field (nSCF) problem, as well as accelerating the direct inversion in the iterative subspace (DIIS) technique to solve the SCF problem, the overall computational cost is reduced by a factor of 8-20 compared with directly using sequential quadratic programming (SQP). This approach should be applicable for other constrained minimization problems, and in the immediate future, once gradients are available, the present eDSC/hDSC algorithm should allow for speedy nonadiabatic dynamics simulations.

Heterointerface engineering in mesoporous g-C3N4@MnFe2O4 photocatalysts for superior hydrogen (H2) evolution

Surfaces and interfaces play a pivotal role in heterostructures-based photocatalysts, which regulate the transfer, separation, and migration of photogenerated charge carriers. In this study, p-type MnFe2O4 nanoparticles (NPs) with complementary band structures were purposefully integrated with n-type porous g-C3N4 nanosheets (NSs) through precise interface engineering. The synergies in the g-C3N4@MnFe2O4 nanocomposites (NCs), leading to performance enhancement and functionalities, arise from their optimized mass fractions within the composite. The heterojunction interface formed in NCs possesses uniformly distributed mesopores (<4 nm), abundant active sites, and a high specific surface area (116 m2/g). Mesoporous heterojunctions improve photocatalytic activity by promoting the transfer of photogenerated electrons and holes to the photocatalyst surface. Notably, the optimized NCs, containing 20 wt% MnFe2O4, display the highest hydrogen evolution rate of 3.17 mmol g⁻¹ h⁻¹ (with methanol) and 5.77 mmol g⁻¹ h⁻¹ (with triethanolamine), which is many folds higher than bare MnFe2O4 and porous g-C3N4, using 1.0 wt.% of Pt as co-catalyst. The enhanced performance is corroborated by the efficient separation of photoinduced charge carriers, facilitated by an induced internal electric field arising from the Fermi level differences between the semiconductors. This study provides new insights into the advantages of designing and constructing mesoporous Z-scheme heterojunction photocatalysts for hydrogen evolution.

Enhanced charge carrier transport and defects mitigation of passivation layer for efficient perovskite solar cells

Surface passivation has been developed as an effective strategy to reduce trap-state density and suppress non-radiation recombination process in perovskite solar cells. However, passivation agents usually own poor conductivity and hold negative impact on the charge carrier transport in device. Here, we report a binary and synergistical post-treatment method by blending 4-tert-butyl-benzylammonium iodide with phenylpropylammonium iodide and spin-coating on perovskite surface to form passivation layer. The binary and synergistical post-treated films show enhanced crystallinity and improved molecular packing as well as better energy band alignment, benefiting for the hole extraction and transfer. Moreover, the surface defects are further passivated compared with unary passivation. Based on the strategy, a record-certified quasi-steady power conversion efficiency of 26.0% perovskite solar cells is achieved. The devices could maintain 81% of initial efficiency after 450 h maximum power point tracking.

Hierarchical Nanostructures CuBi2O4 Integrated with Polyaniline Nanofibrous for Boosting Hole Extraction in Carbon-Based Perovskite Solar Cells.

Toward commercialization of carbon-based perovskite solar cells (C-PSCs), it is crucial to innovatively design inorganic hole transport layer materials that excel in extracting and transporting charge carriers to promote their photoelectric conversion efficiency (PCE). In this work, a novel and high-connectivity CuBi2O4-polyaniline nanofibrous (CuBi2O4-PN) reticular structure is created by integrating CuBi2O4 hierarchical microspheres (CuBi2O4 MS) with polyaniline nanofibrous. The introduction of CuBi2O4-PN as a hole transport layer (HTL) notably enhances the contact quality of the devices and substantially reduces the surface defects of C-PSCs. In a comparative analysis under identical experimental conditions, MAPbI3 devices incorporating CuBi2O4-PN HTL demonstrated a PCE of 14.79%, achieving a 44.3% increase over the reference device (10.25%). CuBi2O4-treated C-PSCs retained 89.9% of their original PCE after 45 days in storage, and they demonstrated improved stability over a longer time frame. This remarkable improvement in device performance can be attributed to the effective suppression of nonradiative recombination and the enhancement of the carrier transfer process in the device. Additionally, the unique interconnected reticular structure of CuBi2O4-PN provides efficient pathways for hole transfer, significantly contributing to the enhanced efficiency of the device.

Synthesis of a novel bismuth molybdite/iron oxide thin film for oxytetracycline degradation in a photoelectrocatalytic system

In this study, heterostructures based on Bismuth molybdite/iron oxide (Bi2MoO6/Fe2O3) thin films were fabricated by a dip-coating technique using precursor solutions. The heterostructures were deposited on fluorine-doped tin oxide glass substrates. From a detailed characterization using X-ray diffraction and X-ray photoelectron spectroscopy, the formation of the orthorhombic phase for Bi2MoO6 and the co-existence of hematite and maghemite in Fe2O3 was demonstrated. Meanwhile, the field emission scanning electron microscopy cross-section images confirm the formation of well-defined Bi2MoO6 film under the Fe2O3 deposition. The optical band gap energies for the heterostructure obtained were estimated from the diffuse reflectance spectra and ranged from 2.3 to 3.5 eV. Photoluminescence analysis revealed an improved separation and faster transfer of photogenerated electrons and holes for the Bi2MoO6/Fe2O3 (Het) film. The best oxytetracycline (OTC) removal percentage through photoelectrocatalytic treatment was 96.85% using the Het. Besides, were carried out the variation of parameters which affect the OTC photoelectrocatalytic degradation as pH, potential applied, and scavenger assay. The 1O2 was the oxidant predominate, which attack the OTC ring to initiate and accelerate the degradation process. Based on the analysis of degradation intermediates and characteristics of Bi2MoO6/Fe2O3, possible degradation pathways and mechanisms of OTC were displayed. An enhancement of oxytetracycline degradation efficiency of Het fabricated compared to pristine oxides was achieved mainly due to avoid the charge recombination of photogenerated electron-hole pairs provided by Direct Z-scheme heterostructure. Finally, the Het fabricated represents a promising material for efficient and sustainable pharmaceutical removal applications.

Piezoelectric Photocatalytic Degradation of Formaldehyde based on BFO@OCN Heterojunctions

Piezoelectric photocatalysts represent a new class of environment-cleaning materials containing a self-electricity nanogenerator. Wind is one of the common energy sources in the natural environment. The piezoelectric field generated by the action of wind on piezoelectric materials can promote the adsorption of organic pollutants and also facilitate the transfer and separation of photogenerated carriers, thereby improving the efficiency of photocatalytic degradation of formaldehyde. This work developed a BFO@OCN heterojunction composite combing BiFeO3 nanocubes (BFO) and g-C3N4 nanosheets with oxygen vacancies (OCN). This piezoelectric photocatalyst exhibited high activity in degradation of formaldehyde in gas under light irradiation. Within 90min, the formaldehyde concentration reduced from 1.50 ppm to 0.68 ppm, almost 2 times higher than the pure CN. This enhanced catalytic performance can be attributed to the synergistic interplay between the wind-induced piezoelectric field generated by BFO nanocubes in wind and the heterojunction with oxygen vacancies from g-C3N4 nanosheets. The piezoelectric field promoted the transfer of photoelectrons and holes in opposite directions, which could inhibit their recombination. Meanwhile, it also induced the generation of oxygen vacancies from g-C3N4 nanosheets. Our research findings provided a feasible strategy for developing high-efficiency piezoelectric photocatalysts, which could be decorated on the car outer-surface for self-cleaning and air purification under sunlight irradiation.

Photoinduced Nonadiabatic Dynamics of a Single-Walled Carbon Nanotube-Porphyrin Complex.

Single-walled carbon nanotubes (SWCNTs) have gained a lot of attention in the past few decades due to their promising optoelectronic properties. In addition, SWCNTs can form complexes that have good chemical stability and transport properties with other optical functional materials through noncovalent interactions. Elucidating the detailed mechanism of these complexes is of great significance for improving their optoelectronic properties. Nevertheless, simulating the photoinduced dynamics of these complexes accurately is rather challenging since they usually contain hundreds of atoms. To save computational efforts, most of the previous works have ignored the excitonic effects by employing nonadiabatic carrier (electron and hole) dynamics simulations. To properly consider the influence of excitonic effects on the photoinduced ultrafast processes of the SWCNT-tetraphenyl porphyrin (H2TPP) complex and to further improve the computational efficiency, we developed the nonadiabatic molecular dynamics (NAMD) method based on the extended tight binding-based simplified Tamm-Dancoff approximation (sTDA-xTB), which is applied to study the ultrafast photoinduced dynamics of the noncovalent SWCNT-porphyrin complex. In combination with statically electronic structure calculations, the present work successfully reveals the detailed microscopic mechanism of the ultrafast excitation energy transfer process of the complex. Upon local excitation on the H2TPP molecule, an ultrafast energy transfer process occurs from H2TPP (SWCNT-H2TPP*) to SWCNT (SWCNT*-H2TPP) within 10 fs. Then, two slower processes corresponding to the energy transfer from H2TPP to SWCNT and hole transfer from H2TPP to SWCNT take place in the 1 ps time scale. The sTDA-xTB-based electronic structure calculation and NAMD simulation results not only match the previous experimental observations from static and transient spectra but also provide more insights into the detailed information on the complex's photoinduced dynamics. Therefore, the sTDA-xTB-based NAMD method is a powerful theoretical tool for studying the ultrafast photoinduced dynamics in large extended systems with a large number of electronically excited states, which could be helpful for the subsequent design of SWCNT-based functional materials.

Effect of Halide Ions on the TiO2-mediated Photocatalysis of Carbendazim in Aqueous Medium Under Near-ultraviolet Light Irradiation

The degradation of carbendazim (CBZ) through TiO2 photocatalysis, in the presence of halide ions and under near-UV light irradiation, was investigated. HPLC–MS technique was used to characterize the photoproducts. Spectrophotometric analysis showed that CBZ degraded slowly in TiO2 aqueous dispersions containing no salt (CBZ conversion of 6% after ca. 5 h of irradiation). The photodegradation efficiency increased particularly by addition of bromide salts. Indeed, CBZ reached complete degradation after ca. 30 min at the maximum concentration of NaBr used (0.05 M). Two significant aspects have emerged from the data analysis: the bromide role is to cause inhibition of the electron–hole recombination, a reaction known to be competitive with the reactive process; CBZ photodegradation is especially initiated by direct hole transfer pathway, whereas the OH• role is crucial in the catalyst regeneration process. Degradation attempts under sunlight appeared promising for a more sustainable photocatalytic process.

{Co4O4} Cubanes in a conducting polymer matrix as bio-inspired molecular oxygen evolution catalysts

Exploration of efficient molecular water oxidation catalysts for long-term application remains a key challenge for the conversion of renewable energy sources into fuels. Cuboidal {Co4O4} complexes keep attracting interest as molecular water oxidation catalysts as they combine features of both heterogeneous and homogeneous catalysis with bio-inspired motifs. However, the application of many cluster-based catalysts for the oxygen evolution reaction still requires new stabilization strategies. Drawing inspiration from the stabilizing effects of natural polymers, we introduce a conductive polymer-hybrid approach to covalently immobilize {Co4O4} cubane oxo clusters as oxygen evolution catalysts. Polypyrrole is applied as an efficient p-type conducting polymer that promotes hole transfer during the oxygen evolution reaction, resulting in higher turnover frequency compared to the pristine {Co4O4} oxo cluster and heterogeneous Co-oxide benchmarks. The asymmetric coordination of {Co4O4} not only mitigates catalyst decomposition pathways, but also increases the catalytic efficiency by exposing a directed cofacial dihydroxide motif during catalysis.