Hybrid Photocatalyst Research Articles

Au depositing and Mg doping synergistically regulates an In2O3 photocatalyst for promoting CO2 reduction and CH4 exclusive generation

Mg–Au bimetallic functional sites modified In2O3 nanoflowers hybrid photocatalysts with exceptional activities are successfully fabricated, attributed to the enhanced CO2 adsorption and activation ability and optimized band gap structure.

A covalent organic framework based on BOPHY/TiO2 hybrid photocatalysts for solar driven hydrogen production

Here we show the improvement in solar driven H2 production due to the synergy between a novel BOPHY based COF and TiO2.

An NIR light-driven AgBiS2@ZIF-8 hybrid photocatalyst for rapid bacteria-killing.

Bacterial infection is the most common risk factor that causes the failure of implantation surgery. Therefore, the development of biocompatible implants with excellent antibacterial properties is of utmost importance. In this study, NIR light-driven AgBiS2@ZIF-8 hybrid photocatalysts for rapid bacteria-killing were prepared. AgBiS2@ZIF-8 exhibited excellent photocatalytic activity due to the rapid transfer of photoelectrons from AgBiS2 to ZIF-8, resulting in abundant reactive oxygen species (ROS) to kill bacteria. Meanwhile, AgBiS2@ZIF-8 exhibited a noteworthy photothermal effect, which could effectively convert NIR light into heat. Subsequently, the NIR light-driven antibacterial activity of AgBiS2@ZIF-8/Ti against S. aureus and E. coli was studied. The experimental results showed that AgBiS2@ZIF-8 displayed enhanced photodynamic therapy (PDT) and photothermal therapy (PTT) performance. Under irradiation with 808 nm NIR light for 10 min, AgBiS2@ZIF-8/Ti could effectively eliminate 98.55% of S. aureus in vitro, 99.34% of E. coli in vitro and 95% S. aureus in vivo. At the same time, AgBiS2@ZIF-8/Ti had good biocompatibility. Therefore, AgBiS2@ZIF-8/Ti showed potential as an antibacterial material, which provided a strategy to fight polymicrobial infections.

Recent Advances in Efficient Photocatalytic Degradation Approaches for Azo Dyes

In recent decades, the textile industry has contributed to continuous pollution in the environment. Synthetic dyes which are commonly found in waste water are azo, sulfur, anthraquinone, triphenylmethyl, indigoid, and phthalocyanine derivatives. These pollutants block the light penetration in water bodies and prevent photosynthesis activity, thereby affecting aquatic life. As an environmental crisis, several technologies have been explored to control pollution. Among all the techniques, the photocatalysis process is considered as a green, simple, and economical process. To improve the photocatalytic activity, researchers worldwide have investigated various photocatalysts such as metal oxides, metal ferrites, and heterostructured nanocomposites. The major goal of this review article is to propose a high-performing, cost-effective hybrid photocatalyst reported to date for prospective azo dye pollutant remediation. This review article also aimed to highlight the challenges and uncertainties associated with dye degradation in the photocatalytic process.

PFAS Degradation from Water by Using Metal Oxide as Photocatalyst

The recalcitrant nature of perfluoroalkyl substances (PFAS) urge scientists to discover solutions to permanently remove PFAS contaminations from water with less energy in contrast to incineration. In this presentation, we will introduce a duo-functional tri-metallic-oxide (f-TMO) hybrid photocatalyst that was synthesized via a facile process, which displayed both high adsorption capacity and high defluorination rate of a series of PFAS including PFOA, PFOS, PFHpA, PFHxA and PFBA due to the generated holes/electrons (h+/e-) and multi-radicals such as O2 •- and SO4 •- (Samuel, Shang, Niu. Chemosphere , 293 (2022) 133568). The Langmuir adsorption capacities up to 827.84 and 714.46 mg g-1 along with the adsorption efficiency of 99.8% and 99.4% for PFOS and PFOA were respectively achieved. A defluorination ratio of as high as 74.8% with PFOA and a ratio up to 67.6% with PFOS were respectively received. Over 98% PFOA molecules were degraded within as fast as 15 min under initial concentrations ranging from 1 ppb to 1000 ppb, which demonstrates an excellent degradation kinetics. After degradation, the PFOA residuals were as low as 10 ng L-1 in industrial wastewater with an initial concentration of 1 ppb. Moreover, as high as 95.5% degradation efficiency of PFOS was obtained within 300 min. The high physical adsorption capacity and high defluorination rate make this f-TMO catalyst promising applications in removing PFAS from a broad range of water sources. Keywords: Perfluoroalkyl substances (PFAS); Photocatalytic degradation; Water Remediation

An S-scheme heterointerface-engineered high-performance ternary NiAl-LDH@TiO2/Ti3C2 MXene photocatalytic system for solar-powered CO2 reduction to produce energy-rich fuels

While there is much potential for photocatalytic CO2 reduction, poor light absorption and high recombination rates of photogenerated charges limit its effectiveness. To address these challenges, we systematically developed a heterointerface-engineered ternary hybrid photocatalyst comprising NiAl-layered double hydroxide (LDH), titanium dioxide (TiO2), and titanium carbide (Ti3C2) MXene via an in situ growth approach. As a result of the unique combination of these three components, the synthesized ternary NiAl-LDH@TiO2/Ti3C2 photocatalyst demonstrated broad light absorption spanning across the ultraviolet, visible, and near-infrared regions, as well as elevated CO2 adsorption capacity. In situ-irradiated X-ray photoelectron spectroscopy and electron paramagnetic resonance analyses provided compelling evidence for an unconventional S-scheme charge transfer mechanism in the ternary system that effectively separates the charges and suppresses recombination, allowing NiAl-LDH to maintain its strong reducing capacity and TiO2 to maintain its robust oxidizing capacity. Utilizing the complementary and synergistic properties of these three components (NiAl-LDH, TiO2, and Ti3C2), an optimized ternary NiAl-LDH@TiO2/Ti3C2 photocatalyst with 30 wt% Ti3C2 exhibited extraordinary solar-driven CO2 reduction performance with a remarkable 99 % CO selectivity against competitive H2 production and a high apparent quantum yield of 0.81 at 365 nm. Additionally, the ternary photocatalyst exhibited excellent stability, maintaining its performance capacity over multiple CO2 reduction cycles. This work provides a fresh perspective on designing and creating efficient ternary S-scheme photocatalytic systems for solar-driven CO2 reduction and highlights the potential for energy-rich fuel production.

A hierarchical 3D hybrid CoAl-layered double hydroxide/TiO2/Ti3C2 MXene S-scheme photocatalyst with 2D/0D/2D contact interfaces for sustainable pollutant degradation

Environmental pollution, particularly that derived from waterborne antibiotics, is a rising concern because of its detrimental effects on aquatic ecosystems and human health. Hence, in this study, we present a hierarchical 3D-structured hybrid photocatalyst comprising a CoAl-layered double hydroxide (LDH), TiO2, and Ti3C2 MXene synthesized using an in situ hydrothermal method. Various characterization techniques revealed that the hybrid CoAl-LDH/TiO2/Ti3C2 photocatalyst exhibited improved optical absorption, and the tailored 2D/0D/2D contact interfaces among the constituents enhanced charge migration and minimized electron-hole recombination. The results of electron paramagnetic resonance and in situ-irradiated X-ray photoelectron spectroscopy analyses confirmed that the hybrid photocatalyst follows an S-scheme mechanism that not only promotes the separation of photoinduced electron-hole pairs but also preserves their robust redox capability. The amalgamation of the three components resulted in synergistic advantages. Consequently, the optimized CoAl-LDH/TiO2/Ti3C2 photocatalyst exhibited remarkable performance in degrading and mineralizing the antibiotic diclofenac sodium (DFS) and the dyes rhodamine B and indigo carmine, surpassing its constituents and previously reported photocatalysts. Furthermore, the hybrid retained high efficiency across multiple cycles, underscoring its potential reusability. Therefore, this study demonstrates the potential of the developed hybrid photocatalyst for sustainable water treatment, thereby fostering cleaner aqueous environments.

In Situ Synthesis of Bi2S3/BiFeO3 Nanoflower Hybrid Photocatalyst for Enhanced Photocatalytic Degradation of Organic Pollutants.

Photocatalytic degradation of Malachite Green oxalate (MG) in a water body is of significant importance to our health protection, as it could cause various serious diseases. However the photocatalytic activity of most catalysts is still unsatisfactory, due to the poor reactive oxygen species production as a result of sluggish charge separation. Here, innovative nanoflower-shaped Bi2S3/BiFeO3 heterojunctions are prepared via a facile sol-gel method, exhibiting an enhanced reactive oxygen species generation, which leads to the excellent photocatalytic performance toward MG degradation. We verify that interfacing BiFeO3 with Bi2S3 could form a fine junction and offers a built-in field to speed up charge separation at the junction area; as a result, this shows much higher charge separation efficiency. By virtue of the aforementioned advantages, the as-prepared Bi2S3/BiFeO3 heterojunctions exhibit excellent photocatalytic performance toward MG degradation, where more than 99% of MG is removed within 2 h of photocatalysis. The innovative design of nanoflower-like Bi2S3/BiFeO3 heterojunctions may offer new viewpoints in designing highly efficient photocatalysts for environmentally related applications.

Synergistic adsorption and kinetic studies of heterostructured g-C3N4/TiO2 nano-photocatalyst under visible light for enhanced CO2 reduction.

Graphitic carbon nitride (g-C3N4) and titanium dioxide (TiO2) were synthesized using sol-gel and ultrasonic impregnation technique followed by calcination for photocatalytic CO2 reduction. The nano-photocatalysts were analyzed for their morphological, structural, and optical characteristics. Scanning electron microscopy (SEM) revealed the presence of spherical and layered sheet-like nanoparticles, as well as the occurrence of minor aggregations. The ultraviolet-visible spectroscopy (UV-vis) revealed that g-C3N4 has good photocatalytic properties with a medium band gap (2.7eV), and TiO2 has high charge transfer potentials, robust oxidation properties, and high band gap (3.20eV). However, the larger band gap makes it unresponsive in the visible light spectrum. In order to circumvent this constraint, a hybrid heterostructured g-C3N4/TiO2 catalyst with different compositions, viz., 1:1, 1:2, and 2:1, were fabricated using the ultrasonic impregnation technique followed by calcination process. The optical band gap of g-C3N4/TiO2 nanocomposite shows a red shift towards 2.85eV from 3.20eV for bare TiO2, inferring enhanced absorption in the visible light region. Further, the photocatalytic experiments were performed using visible light sources for all the catalysts. The g-C3N4/TiO2 (2:1) reported higher photocatalytic activity due to its reduced crystallite size of 12.94nm which were investigated using X-ray diffraction analysis (XRD) and lower band gap of 2.85eV. The study infers that hybrid photocatalyst enhances the visible light absorption, electron-hole (e - /h +) pair separation rate, and photocatalytic reduction of CO2. In addition, two adsorption models Langmuir and Freundlich were used and adsorption kinetic data were fitted to pseudo-first-orderreaction for all thefive catalysts. The adsorption isotherm of CO2 by g-C3N4/TiO2 (2:1) wellfitted by the Freundlich adsorption equation. On the basis of adsorption magnitude (n) values (1.74), it was found that the interaction between CO2 molecules and g-C3N4/TiO2 occurs according to the chemisorption mechanism. The kinetic study infers that the highest value of apparent rate constant (kapp) was exhibited by g-C3N4/TiO2 (2:1), which indicates that the products predominate at equilibrium.

Defect-Regulated Two-Dimensional Superlattice of Holey g-C3N4-TiO2 Nanohybrids: Contrasting Influence of Vacancy Content on Hybridization Impact and Photocatalyst Performance.

Defect engineering provides an effective way to explore efficient nanostructured catalysts. Herein, we synthesize defect-regulated two-dimensional superlattices comprising interstratified holey g-C3N4 and TiO2 monolayers with tailorable interfacial coupling. Using this interfacial-coupling-controlled hybrid system, a strong interdependence among vacancy content, performance, and interfacial coupling was elucidated, offering key insights for the design of high-performance catalysts. The defect-optimized g-C3N4-TiO2 superlattice exhibited higher photocatalytic activity toward visible-light-induced N2 fixation (∼1.06 mmol g-1 h-1) than defect-unoptimized and disorderly assembled g-C3N4-TiO2 homologues. The high photocatalytic performance of g-C3N4-TiO2 was attributed to the hybridization-induced defect creation, facilitated hydrogenation of adsorbed nitrogen, and improvement in N2 adsorption and charge transport. A comparison of the defect-dependent photocatalytic activity of g-C3N4, g-C3N4 nanosheets, and g-C3N4-TiO2 revealed the presence of optimal defect content for improving photocatalytic performance and the continuous increase of hybridization impact with the defect content. Sophisticated mutual influence among defect, electronic coupling, and photocatalytic ability underscores the importance of defect fine control in exploring high-performance hybrid photocatalysts. Along with the DFT calculation, the excellent photocatalyst performance of defect-optimized g-C3N4-TiO2 can be ascribed to the promotion of the uphill *N hydrogenation step as well as to enhancement of N2 adsorption, charge transfer kinetics, and mass transports.

Synthesis of novel maghemite (γ-Fe2O3)-decorated g-C3N4 nano-tubes (g-C3N4 NTs/γ-Fe2O3) photocatalytic nano-composite for ultrafast degradation of organics in wastewater: Insight into the mechanism of photoexcited charge separation

In this study, to enhance the photodegradation of organic pollutants including Methyl blue (MB) and Methyl orange (MO), mesoporous tubular g-C3N4/γ-Fe2O3 (FCN) nano-composite synthesized via facile procedures. FT-IR and XRD data proved the existence of maghemite (γ-Fe2O3) nanoparticles on the g-C3N4 nano-tubes. Experimental data showed that among fabricated photocatalysts, FCN exhibited the highest activity rate toward the photodegradation of MB (%96.1/60 min) and MO (%98.3/120 min) with an excellent kinetic rate of 0.0509 min−1 (MB) and 0.0352 min−1 (MO) under visible light and considerable photocatalytic stability after six cycles. In addition, the visible light-harvesting-capability of FCN enhanced compared to unequipped forms of g-C3N4 (BCN and CNNTs), surprisingly functioning under irradiation of photons greater than 900 nm, proving the synergistic role of γ-Fe2O3 nanoparticles not only in harvesting visible light but also in hindering electron-hole recombination. BET analysis showed mesoporous structure, the highest SSA and pore volume (55.623 m2/g, 0.1699 cm3/g) for FCN, indicating more active sites and enhanced target molecules adsorption, then augmented photocatalytic performance in comparison to the rest of the samples. Finally, FCN generated an excellent photocurrent density (3.76 μA/cm2) with the least arc radius, introducing a high-potential hybrid photocatalyst to the research field.

Enhanced selectivity and charge transfer over highly dispersed Cd0.2Zn0.8S/meta-kaolinite catalysts for CO2 photoreduction

In this work, a novel hybrid photocatalyst consisting of Cd0.2Zn0.8S grown on a defect-rich meta-kaolinite nanosheet (CZS/MK) composite was investigated for the photoreduction of CO2 to CO in the presence of simulated sunlight with high selectivity. CZS/MK displayed a CO yield of 21.3 µmol g−1h−1 with a remarkable selectivity of 97.4 % without any co-catalyst and sacrificial reagent. The addition of MK to the catalyst altered CZS hydrophilicity and improved CO selectivity. Moreover, kaolinite is relatively inexpensive, and the defects in MK can optimize pore size distribution and structure of Cd0.2Zn0.8S, resulting in improved dispersion and a higher quantity of exposed active sites on the composite material. Experimental investigations combined with DFT calculations illustrated that the adsorption configuration involving the introduction of kaolinite was more favorable for CO2 activation, which ultimately decreased the formation barrier of key intermediate *COOH. In situ Fourier transform-infrared analysis indicated that Cd0.2Zn0.8S/MK tended to produce vital *COOH intermediates, thereby achieving higher CO conversion efficiency. This study provides novel insights into the utilization of kaolinite-based catalysts for enhancing CO2 photoreduction.

Cross-linked cellulose beads as an eco-friendly support for ZnO/SnO2/carbon xerogel hybrid photocatalyst: Exploring the synergy between adsorption and photocatalysis under simulated sunlight

This paper explores the application of cross-linked cellulose beads as a sustainable and cost-effective support for the ZnO/SnO2/carbon xerogel hybrid photocatalyst. The application of the developed photocatalytic beads, named CB-Cat, was directed at a simultaneous adsorption/photocatalysis process, which was carried out under simulated sunlight. The characterization of the CB-Cat indicated a good dispersion of the photocatalyst of choice throughout the cellulose matrix, confirming its incorporation into the cellulose beads. Furthermore, it is possible to observe the presence of the photocatalyst on the surface of the CB-Cat, confirming its availability for the photonic activation process. The results showed that the simultaneous adsorption/photocatalysis process was optimal for enhancing the efficiency of methylene blue (MB) removal, especially when compared to the isolated adsorption process. Additionally, the regeneration of the CB-Cat between cycles was favorable toward the maintenance of the MB removal efficiency, as the process carried out without regeneration displayed significant efficiency drops between cycles. Finally, the mechanism evaluation evidenced that hydroxyl and superoxide radicals were the main responsible for the MB photocatalytic degradation during illumination with simulated sunlight.

Defect engineering in 0D/2D TiO2/g-C3N4 heterojunction for boosting photocatalytic degradation of tetracycline in a tetracycline/Cu2+ combined system

It has been increasingly significant to take advantage of defect engineering in hybrid photocatalysts, aiming to showing novel properties in the remediation of combined pollution such as antibiotic-heavy metal pollution. Herein, a hierarchical 0D/2D TiO2/g-C3N4 heterojunction was fabricated and defects were introduced into the binary-hybrid structure with separate plasma treatment for the each single component. Results show that defect construction on TiO2/CN can exhibit “anisotropic-trapping” effect, where TiO2/D-CN shows stimulation effect while D-TiO2/CN and D-TiO2/D-CN show inhibition on the degradation of tetracycline in the presence of Cu2+. TiO2/D-CN can inhibit the accumulation of Cu2+ and avoid the coverage of active site during the photocatalytic process in contrast to the non-defective or other defective materials. Simultaneously, the formed Cu sites exhibited surface plasmon resonance effect that can enhance the absorption of light, further promoting the photocatalytic degradation of tetracycline. These findings provide new insights into defect construction on binary-heterojunction for the treatment of combined pollution in water.

Double S‐Scheme Polydopamine/TiO2/Chlorophyll as Stable and Efficient Green Photoelectrocatalyst

AbstractInspired by natural photosynthesis, a new green catalyst with better photocatalytic properties was obtained. Nanostructured TiO2, a cheap cost natural Chlorophyll‐a as an electron promotor and a mussel‐inspired polydopamine (PD) bio adhesive were synergistically combined in the double S‐scheme hybrid photocatalysts The role of PD as a bridging molecule between the pigments of Chl and TiO2 was clearly demonstrated by improved charge transfer and recombination rate. Methylorange as a probe molecule was used to test the stability and efficiency of the new photocatalyst. This challenging approach on obtaining new green bioinspired catalysts avoiding critical raw materials is in line with the new vision on catalysts. The results of this study show the effectiveness and stability of the new photocatalyst. Based on the combined effect of PD functionalization and Chl sensitization, the NT/PD‐Chl heterostructure photocatalyst had the best photo(electro)catalytic performance for MO degradation which was shown to be 97.74 % after 180 min.

Regulating interfacial coupling of 1D crystalline g-C3N4 nanorods with 2D Ti3C2Tx MXene for boosting photocatalytic CO2 reduction

Two-dimensional (2D) layered photocatalysts coupled with 2D Ti3C2Tx (T = OH, O, or F) MXene cocatalysts in 2D/2D configuration have been extensively studied for use in artificial photosynthesis. Unfortunately, the overall photoreaction efficiency of these cocatalysts is often limited by weak 2D/2D interfacial van der Waals interactions, high interfacial electrostatic barriers, and slow interfacial charge transfer. In this study, 1D crystalline g-C3N4 (CCN) nanorods are grown along the c-axis using the molten-salt method and assembled onto a 2D Ti3C2Tx substrate by freeze-drying-assisted interfacial coupling, forming a unique Schottky junction photocatalyst in a 1D/2D configuration with interfacial hydrogen bonds. Transfer of photoelectrons in the CCN nanorods could along the radial π-conjugated plane to the hydrogen-bonded 2D Ti3C2Tx in the 1D/2D configuration is more efficient than the slow interlayer charge transfer in catalysts with a conventional 2D/2D configuration. Consequently, the optimized 1D-CCN/2D-Ti3C2Tx hybrid photocatalyst assembled by freeze-drying (TC/CCN-FD) exhibited an outstanding photocatalytic CO2 reduction activity at a rate of 2.13 μmol g1 h1, being 5.6 and 8.9 times more efficient than the pristine 1D CCN and 2D bulk g-C3N4 counterparts, respectively. Moreover, the selectivity towards the multielectron reduction product (CH4) was significantly enhanced over TC/CCN-FD owing to the faster interfacial charge transfer across the CCN/Ti3C2Tx interface and the higher density of photoelectrons on the Ti3C2Tx cocatalysts. This work will inspire further studies on suppressing the interfacial charge transfer barrier by matching the interfacial crystal orientation and strengthening the interfacial interactions.

Computationally engineering optoelectronic properties and photocatalytic performance in graphene quantum dot/platinum(II) complex photocatalysts

This study delves into the impact of various substituents on bipyridyl Pt(II) bisstilbenylacetylide complexes when attached to Graphene quantum dots (GQDs), a material with promising photocatalytic potential. Using density functional theory calculations, the research uncovers that the substituents significantly alter properties of the resulting nanocomposites. These include the geometric and electronic structures, optical absorption profiles, charge transfer configurations, and chemical reactivity. Electron-withdrawing groups cause blueshifts in absorption peaks, while electron-donating ones induce redshifts. These shifts are more pronounced when the complexes are attached to GQDs. The attachment of GQDs also impacts the molecular orbital structure, stabilizing the highest occupied molecular orbital (HOMO), but destabilizing the lowest unoccupied molecular orbital (LUMO). Furthermore, the incorporation of GQDs into the composite enhances overall stability while diminishing reactivity. The formation of the nanocomposite reduces the energetic favorability of electron injection and regeneration processes. Interestingly, the substituents affect the charge transfer length more significantly for nanocomposites compared to isolated complexes. Overall, this study provides valuable insights into fine-tuning optoelectronic and photocatalytic properties of GQD hybrid photocatalysts, useful in applications like solar energy conversion and pollutant degradation. These findings significantly advance the understanding of the structure–function relationship in GQD nanocomposites for photocatalysis.

Visible-light activation of carbon-supported BiVO4 photocatalysts

Bismuth vanadate (BiVO4) has gained attention for several applications, including photocatalysis applied to water purification technologies. This applies to the most stable BiVO4 polymorph (monoclinic scheelite), exhibiting photocatalytic activity under visible-light irradiation. However, this semiconductor presents some limitations, namely the cost and low adsorption capacity for organic pollutants. Finding green chemical strategies aiming at a more sustainable use of this semiconductor is the subject of the present research. By the hydrothermal carbonization of κ-carrageenan, a biopolymer extracted from red seaweeds, we describe the preparation of monoclinic BiVO4 supported on carbon spheres. These hybrid materials show visible-light photocatalytic activity to remove tetracycline (TC) in water through a hydroxyl radical mechanism. The hybrid photocatalysts feature adequate wavelength range for photon harvesting, good adsorption capacity, durability, and the ability to reuse in subsequent catalytic steps, thus making them less costly and more sustainable.

Hydrophilic calix[4]arene dye-sensitized Co/g-C3N4 composites with Co single atoms for enhanced visible-light-driven photocatalysis

Single-atom hybrid photocatalysts (Co/g-C3N4/C4EOP) composed of hydrophilic calixarene dyes (C4EOP) and graphite-phase carbon nitrite with monodispersed Co atoms (Co/g-C3N4) are prepared by a facile solution impregnation method, and their photocatalytic performances are evaluated in visible light-driven H2 evolution from water and CO2 conversion. The optimized Co/g-C3N4/C4EOP (1.0 wt%) catalyst exhibits moderate H2 production activity (511 μmol g−1 h−1) and good durability within 60 h (TONC4EOP value of 2255) under visible light. In contrast, the Co/g-C3N4/C4BTP (1.0 wt%) and Co/g-C3N4/M-EOP (1.0 wt%) show much lower activities than Co/g-C3N4/C4EOP (1.0 wt%) under the same conditions. This could be attributed to the higher molar extinction coefficient and better hydrophilicity of C4EOP compared to C4BTP with hydrophobic alkane groups and M-EOP with single D-π-A chain. In addition, Co/g-C3N4/C4EOP (1.0 wt%) catalyst displays highly selective photocatalytic activity for CO2 reduction to CO. This work provides a promising example for the development of efficient dye-sensitized photocatalytic system based on g-C3N4 with non-noble metal for the chemical utilization of solar energy.

An Unlocked Two-Dimensional Conductive Zn-MOF on Polymeric Carbon Nitride for Photocatalytic H2O2 Production.

Developing highly efficient catalytic sites for O2 reduction to H2O2, while ensuring the fast injection of energetic electrons into these sites, is crucial for artificial H2O2 photosynthesis but remains challenging. Herein, we report a strongly coupled hybrid photocatalyst comprising polymeric carbon nitride (CN) and a two-dimensional conductive Zn-containing metal-organic framework (Zn-MOF) (denoted as CN/Zn-MOF(lc)/400; lc, low crystallinity; 400, annealing temperature in oC), in which the catalytic capability of Zn-MOF(lc) for H2O2 production is unlocked by the annealing-induced effects. As revealed by experimental and theoretical calculation results, the Zn sites coordinated to four O (Zn-O4) in Zn-MOF(lc) are thermally activated to a relatively electron-rich state due to the annealing-induced local structure shrinkage, which favors the formation of a key *OOH intermediate of 2e- O2 reduction on these sites. Moreover, the annealing treatment facilitates the photoelectron migration from the CN photocatalyst to the Zn-MOF(lc) catalytic unit. As a result, the optimized catalyst exhibits dramatically enhanced H2O2 production activity and excellent stability under visible light irradiation.