Cascade Charge Transfer Research Articles

Purposefully construction of ZnIn2S4/CdIn2S4/Co3O4 synergistic mix-heterojunction for enhanced CO2 photoconversion and H2 evolution reaction via cascade charge transfer

The high-dispersed nano complex ZnO/Co3O4 was first prepared by calcining the ZIF-8@ZIF-67 in Air. Then, the ternary mix-heterojunction ZnIn2S4/CdIn2S4/Co3O4 (CdIn2S4/Z/C) was first in situ constructed by introducing nano complex ZnO/Co3O4 into the CdIn2S4 precursor solution via a solvent thermal reaction. Overall, the CdIn2S4/Z/C photocatalyst exhibits excellent performance in the photoconversion of CO2 and H2O, which increased by 18.1%∼34.1% for CO, 36.8%∼73.9% for H2, and 21.1%∼40.6% for syngas (CO+H2), respectively, compared with CdIn2S4. The CdIn2S4/Z/C-40 shows the highest H2-evolution rate of 1661.8 μmolg−1h−1, which is 87.5% higher than that of CdIn2S4 (886.3 μmolg−1h−1). The CdIn2S4/Z/C exhibits higher surface S-vacancy concentration, larger specific surface area, stronger light absorption, and photocurrent density than that of CdIn2S4. The band structure reveals that the ZnIn2S4/CdIn2S4/Co3O4 forms a tandem internal electric field at the double heterojunction interface, which is beneficial to improve the migration of photocarrier. This work provides a feasible strategy for constructing synergistic mix-heterojunction photocatalyst for photoconversion of CO2 and H2O.

Cascade charge transfer mechanism optimization of g-C3N4/Bi@Bi2WO6 for efficient 2,4-DCP piezo-photocatalytic degradation

The technique of ultrasonically mediated piezo-photocatalysis shows promising prospects in the fields of environment and energy. However, a more detailed exploration is needed to understand its underlying mechanisms. The present study demonstrates the successful enhancement of piezo-photocatalytic efficiency in a g-C3N4/Bi@Bi2WO6 (ωCBBW) composite by employing a bifunctional strategy. Approximately 91 % of the 2,4-dichlorophenol (2,4-DCP) is degraded by the cooperative interaction of ultrasonic and illumination, which is 1.7 times higher than that under photocatalytic and 2.1 times greater than under piezoelectric. The negative shifted flat band in Mott-Schottky is attributed to the regulation of the internal electric field by the piezoelectric effect, indicating the shielding of the Schottky barrier by the piezoelectric field. The strongest photocurrent density of 7.18 μA/cm2 shows a significant charge conduction behavior. Additionally, the Charge density difference suggests a preferential electron transfer from Bi to Bi2WO6 rather than g-C3N4. Based on work function and ESR spectroscopy, a novel mechanism is proposed for the transition from Type-II to S-scheme charge transfer in the piezo-photocatalytic system. This study establishes the profound influence of heterojunction materials, exhibiting both LSPR and piezoelectric properties, on photon conversion efficiency in piezo-photocatalytic systems, characterized by an augmented photocurrent density.

Enabling Low Nonradiative Recombination Losses in Organic Solar Cells by Efficient Exciton Dissociation

AbstractThe achievement of high performance in organic solar cells (OSCs) is highly dependent on efficient exciton dissociation. However, a comprehensive understanding of the exciton dissociation process under photoexcitation in OSCs remains elusive. Herein, a prototypical system of PM6:Y6 is adopted to explore the exciton dissociation process. An organic semiconductor PCz with distinctive photoexcitation signals from PM6 and Y6 is incorporated as the third component. Femtosecond transient absorption spectroscopy demonstrates clear cascade charge transfer processes in ternary PM6:PCz:Y6 system. These cascade channels contribute to enhancing the efficiency of exciton dissociation. Consequently, the nonradiative recombination energy loss is reduced, resulting in an improved power conversion efficiency (PCE) of OSCs. Furthermore, the reduction of energy loss is verified in different OSCs. When PCz is introduced into the D18:L8‐BO system, a low nonradiative recombination energy loss of 0.175 eV is demonstrated, contributing a PCE of over 19%. This work highlights that the insight of efficient exciton dissociation enables low nonradiative recombination losses for efficient OSCs.

Fabrication of copper porphyrin-ruthenium pincer complex coupled polymer/Cs0.33WO3 Z-scheme composite photocatalyst for highly efficient CO2 conversion

The photocatalytic system that simulates the principle of photosynthesis is considered one of the most promising technologies for converting CO2 into chemical fuels. Herein, copper tetra(4-carboxyphenyl)porphyrin (CuPor)-ruthenium 2,6-bis(5-amino-benzimidazol-2-yl)pyridine pincer complex (RuN3) coupled polymer (CuPor-RuN3) is in-situ polymerized on hexagonal tungsten bronze Cs0.33WO3 (CsWO) nanoparticles to construct a novel CuPor-RuN3/CsWO composite photocatalyst with cascade charge transfer mechanism, where the inorganic–organic Z-scheme heterojunction at the CuPor-RuN3/CsWO interface and the Z-scheme molecular junction (-[CuPor-RuN3]-) within the polymer facilitate photoexcited electrons transferring from CuPor units to RuN3 ones, and finally enriching on Ru sites for boosting the CO2 reduction reaction (CO2RR). Under visible light irradiation and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole serving as electron donor, the resultant CuPor-RuN3/CsWO delivers average CO/CH4 yields up to 4645/89 μmol g-1h−1, corresponding to an overall photoactivity of 10002 μmol g-1h−1, which is 20 times higher than that of the single polymer. These results provide new ideas for exploring high-performance artificial photosynthesis system to convert CO2 into chemical fuels.

Customizing precise, tunable, and universal cascade charge transfer chains towards versatile photoredox catalysis.

The core factors dictating the photocatalysis efficiency are predominantly centered on controllable modulation of anisotropic spatial charge transfer/separation and regulating vectorial charge transport pathways. Nonetheless, the sluggish charge transport kinetics and incapacity of precisely tuning interfacial charge flow at the nanoscale level are still the primary dilemma. Herein, we conceptually demonstrate the elaborate design of a cascade charge transport chain over transition metal chalcogenide-insulating polymer-cocatalyst (TIC) photosystems via a progressive self-assembly strategy. The intermediate ultrathin non-conjugated insulating polymer layer, i.e., poly(diallyl-dimethylammonium chloride) (PDDA), functions as the interfacial electron relay medium, and simultaneously, outermost co-catalysts serve as the terminal "electron reservoirs", synergistically contributing to the charge transport cascade pathway and substantially boosting the interfacial charge separation. We found that the insulating polymer mediated unidirectional charge transfer cascade is universal for a large variety of metal or non-metal reducing co-catalysts (Au, Ag, Pt, Ni, Co, Cu, NiSe2, CoSe2, and CuSe). More intriguingly, such peculiar charge flow characteristics endow the self-assembled TIC photosystems with versatile visible-light-driven photoredox catalysis towards photocatalytic hydrogen generation, anaerobic selective organic transformation, and CO2-to-fuel conversion. Our work would provide new inspiration for smartly mediating spatial vectorial charge transport towards emerging solar energy conversion.

Layer-By-Layer Assembly of Atomically Precise Alloy Nanoclusters Photosystems for Solar Water Oxidation.

Atomically precise metal nanoclusters (NCs) have garnered tremendous attention as light-harvesting antennas in heterogeneous photocatalysis due to unique atomic stacking mode, quantum confinement effect, and enriched active sites. However, metal NCs as photosensitizers suffer from extremely short carrier lifetime, poor photostability, and difficulty in carrier migration, which hinder the wide-spread utilization of metal NCs in solar energy conversion. To solve these problems, herein, Ag-doped glutathione (GSH)-capped gold NCs, i.e., alloy Au1- x Agx @GSH NCs and non-conjugated insulating polymer of poly(diallyl-dimethylammonium chloride) (PDDA) are utilized as the building blocks for layer-by-layer assembly of spatially multilayered alloy NCs/metal oxide (MO) photosystems. The alternately deposited ultrathin PDDA layer in-between Au1- x Agx @GSH NCs on the MO substrate functions as an efficient charge flow mediator to relay the directional photoelectron transfer over Au1- x Agx @GSH NCs, giving rise to the cascade charge transfer chain. This peculiar carrier migration mode endowed by exquisite interface configuration design significantly boosts the unidirectional electron migration from the Au1- x Agx @GSH NCs to the MO substrate, substantially improving the visible-light-driven photoelectrochemical water oxidation performances of MO/(PDDA-Au1- x Agx )n multilayer heterostructured photoanodes. The work will inspire the rational construction of alloy metal NCs-based photosystems for modulating spatially controllable charge transfer pathway for solar energy conversion.

Near-Infrared Self-Assembled Hydroxyl Radical Generator Based on Photoinduced Cascade Electron Transfer for Hypoxic Tumor Phototherapy.

The hydroxyl radical (•OH) is an extremely potent reactive oxygen species that plays a crucial role in photooxidations within the realm of hypoxic tumor therapy. However, the current methods for •OH photogeneration typically rely on inorganic materials that require UV/vis light excitation. Consequently, photogenerators based on organic molecules, especially those utilizing near-infrared (NIR) light excitation, are rare. In this study, the concept of photoinduced cascade charge transfer (PICET), which utilizes NIR heavy-atom-free photosensitizers (ANOR-Cy5) to generate •OH is introduced. The ANOR-Cy5 photosensitizer, with its flexible hydrophobic structure, enables the formation of nanoparticles in aqueous solutions through molecular assembly. PICET involves a symmetry-breaking charge separation-induced localized charge-separated state, transitioning to a delocalized charge-separated state, which governs the efficiency of •OH generation. Thanks to the oxygen-independent nature of •OH generation and its robust oxidative properties, the ANOR-Cy5-based photosensitizer demonstrates highly effective photoinduced anti-cancer effects, even under severely hypoxic conditions. This discovery emphasizes the potential for achieving •OH photogeneration using a single organic molecule through the engineering of molecular self-assembly, thereby opening up new possibilities for phototherapy and beyond.

Ultrafast Cascade Charge Transfer in Multibandgap Colloidal Quantum Dot Solids Enables Threshold Reduction for Optical Gain and Stimulated Emission.

Achieving low-threshold infrared stimulated emission in solution-processed quantum dots is critical to enable real-life applications including photonic integrated circuits (PICs), LIDAR application, and optical telecommunication. However, realization of low threshold infrared gain is fundamentally challenging due to high degeneracy of the first emissive state (e.g., 8-fold) and fast Auger recombination. In this Letter, we demonstrate ultra-low-threshold infrared stimulated emission with an onset of 110 μJ cm-2 employing cascade charge transfer (CT) in Pb-chalcogenide colloidal quantum dot (CQD) solids. In doing so, we investigate this idea in two different architectures including a mixture of multiband gap CQDs and a layer-by-layer (LBL) configuration. Using transient absorption spectroscopy, we show ultrafast cascade CT from large band gap PbS CQD to small band gap PbS/PbSSe core/shell CQDs in LBL (∼2 ps) and mixture (∼9 ps) configurations. These results indicate the feasibility of using cascade CT as an efficient method to reduce the optical gain threshold in CQD solid films.

Integration of Single-Atom Catalyst with Z-Scheme Heterojunction for Cascade Charge Transfer Enabling Highly Efficient Piezo-Photocatalysis.

Piezo-assisted photocatalysis (namely, piezo-photocatalysis), which utilizes mechanical energy to modulate spatial and energy distribution of photogenerated charge carriers, presents a promising strategy for molecule activation and reactive oxygen species (ROS) generation toward applications such as environmental remediation. However, similarly to photocatalysis, piezo-photocatalysis also suffers from inferior charge separation and utilization efficiency. Herein, a Z-scheme heterojunction composed of single Ag atoms-anchored polymeric carbon nitride (Ag-PCN) and SnO2- x is developed for efficient charge carrier transfer/separation both within the catalyst and between the catalyst and surface oxygen molecules (O2 ). As revealed by charge dynamics analysis and theoretical simulations, the synergy between the single Ag atoms and the Z-scheme heterojunction initiates a cascade electron transfer from SnO2- x to Ag-PCN and then to O2 adsorbed on Ag. With ultrasound irradiation, the polarization field generated within the piezoelectric hybrid further accelerates charge transfer and regulates the O2 activation pathway. As a result, the Ag-PCN/SnO2- x catalyst efficiently activates O2 into ·O2 - , ·OH, and H2 O2 under co-excitation of visible light and ultrasound, which are consequently utilized to trigger aerobic degradation of refractory antibiotic pollutants. This work provides a promising strategy to maneuver charge transfer dynamics for efficient piezo-photocatalysis by integrating single-atom catalysts (SACs) with Z-scheme heterojunction.

Incorporation of Cu into Goethite Stimulates Oxygen Activation by Surface-Bound Fe(II) for Enhanced As(III) Oxidative Transformation.

The dark production of reactive oxygen species (ROS) coupled to biogeochemical cycling of iron (Fe) plays a pivotal role in controlling arsenic transformation and detoxification. However, the effect of secondary atom incorporation into Fe(III) oxyhydroxides on this process is poorly understood. Here, we show that the presence of oxygen vacancy (OV) as a result of Cu incorporation in goethite substantially enhances the As(III) oxidation by Fe(II) under oxic conditions. Electrochemical and density functional theory (DFT) evidence reveals that the electron transfer (ET) rate constant is enhanced from 0.023 to 0.197 s-1, improving the electron efficiency of the surface-bound Fe(II) on OV defective surfaces. The cascade charge transfer from the surface-bound Fe(II) to O2 mediated by Fe(III) oxyhydroxides leads to the O-O bond of O2 stretching to 1.46-1.48 Å equivalent to that of superoxide (•O2-), and •O2- is the predominant ROS responsible for As(III) oxidation. Our findings highlight the significant role of atom incorporation in changing the ET process on Fe(III) oxyhydroxides for ROS production. Thus, such an effect must be considered when evaluating Fe mineral reactivity toward changing their surface chemistry, such as those noted here for Cu incorporation, which likely determines the fates of arsenic and other redox sensitive pollutants in the environments with oscillating redox conditions.

Suitable energy avenue for the dimension-matched cascade charge transfer mechanism in a g-C3N4/TS-1 heterostructure co-doped with Au–TiO2 for artificial photosynthetic green fuel production

A Z-scheme g-C3N4/TS-1 heterojunction supported photosensitizer, along with an Au–TiO2 energy avenue, enables selective photocatalytic CO2 reduction to CH4, CO, and H2. This innovative approach enhances green fuel production efficiency effectively.

Regulating photocatalytic CO2 reduction selectivity via steering cascade multi-step charge transfer pathways in 1 T/2H-WS2/TiO2 heterojuncitons

Due to the high stability of CO2 and slow multi-electron transfer kinetics, photocatalytic reduction of CO2 into multi-electron product CH4 with high selectivity is still a big challenge. Herein, multiphasic WS2 nanosheets composed of metallic 1 T phase and semiconducting 2H phase were integrated with TiO2 nanoparticles to construct a novel ternary heterojunction photocatalyst (1 T/2H-WS2/TiO2) for selective photocatalytic CO2 reduction into CH4. In this heterojunction photocatalyst, an efficient cascade charge transfer channel from TiO2 to 2H-WS2 and subsequently transferred to 1 T-WS2 is formed, which accelerates the charge separation and enables enough electrons enriched on the surface of 1 T-WS2 acting simultaneously as the co-catalyst, resulting in the high selectivity of CH4. The optimized 1 T/2H-WS2/TiO2 photocatalyst showed a higher CH4 yield of 36.44 μmol·g−1·h−1 with a selectivity reaching 94.2%, which was much higher than those of TiO2 (41.9%), 1 T-WS2/TiO2 (80.6%) and 2H-WS2/TiO2 (13.4%). This novel design provides a valuable research reference for regulating the photocatalytic CO2 reduction selectivity via steering the cascade multi-step charge transfer pathways through phase engineering.

Fe2 O3 /FePO4 /FeOOH Ternary Stepped Energy Band Heterojunction Photoanode with Cascade-Driven Charge Transfer and Enhanced Photoelectrochemical Performance.

Controlling the charge transfer pathway in semiconductors is an important method to improve charge separation efficiency and enhance photoelectrochemical activity. In this work, a Fe2 O3 /FePO4 /FeOOH nanorod photoanode with stepped energy band structure is prepared by a hydrothermal and water bath method. The charge separation efficiency of the ternary heterojunction is higher than that of the traditional type II heterojunction, which might be due to the efficient cascade charge transfer and separation effect of the ternary stepped energy band heterojunction. The H2 and O2 evolution rates for photoelectrochemical water splitting of Fe2 O3 /FePO4 /FeOOH photoanode are 0.247 and 0.111 μmol min-1 , which is 2.15 and 1.95 times that of the Fe2 O3 /FePO4 photoanode, respectively. The incident photocurrent efficiency (IPCE) of Fe2 O3 /FePO4 /FeOOH photoanode under 365 nm light irradiation is 1.5 and 1.8 times that of Fe2 O3 /FePO4 and Fe2 O3 /FeOOH photoanodes, respectively. This work provides an attractive strategy for solar energy conversion to construct efficient photoelectrochemical photoanode materials.

Decoration of graphene oxide as a cocatalyst on Bi doped g-C3N4 photoanode for efficient solar water splitting

• Improvement of photoelectrocatalytic properties of Bi@g-C 3 N 4 by loading GO. • Enhancement in applied bias photon to current efficiency by cascade charge transfer. • The smallest semicircle in Nyquist plots for Bi@g-C 3 N 4 /GO. To enhance the solar photoelectrocatalytic water splitting, an effective photoanode was designed by electrophoretic depositing of graphene oxide (GO) on FTO/c-TiO 2 /Bi@g-C 3 N 4 . The photoelectrocatalytic performance of g-C 3 N 4 was improved by Bi doping and GO loading as a cocatalyst on the surface of photoanode through the efficient charge cascade to increase an effective charge separation and reduce activation barriers for oxygen evolution reaction. The current–potential curve of Bi@g-C 3 N 4 /GO displayed about five and two times more photocurrent density (0.3 mA cm −2 at 1.23 V vs RHE) with respect to those of g-C 3 N 4 and Bi@g-C 3 N 4 , following with a 110 and 80 mV cathodically shifted onset potential, respectively. The conduction band edge was calculated using the flat band potential of the photocatalysts which was estimated by Butler-Gartner model. GO loading leads to yield the photo-voltage of 176 mV compared with 81 and 113 mV for g-C 3 N 4 and Bi@g-C 3 N 4 , respectively. The optimum of thickness of GO cocatalyst was 0.9 µm. If the thickness exceeds this optimum value, the recombination centers increase and active sites of photocatalytic layer are blocked. The charge separation and injection efficiency for Bi@g-C 3 N 4 /GO photoanode were determined by using H 2 O 2 as an effective hole scavenger. Among fabricated electrodes, Bi@g-C 3 N 4 /GO electrode represented the lowest charge transfer resistance. The results showed that much improvement in photoelectrocatalytic performance was achieved by GO loading on the surface of photoanode with respect to Bi doping in the structure of photocatalyst.

ITIC derivative acceptors for ternary organic solar cells: fine-tuning of absorption bands, LUMO energy levels, and cascade charge transfer

Simply adding ITIC derivatives, which can form a cascade energy alignment between the host donor and acceptor LUMO levels, as a small amount (5 wt%) of A2 acceptor molecules in TOSCs improved the PCE by up to 10% more than that of the BOSC system.

Unleashing non-conjugated polymers as charge relay mediators.

The core factors affecting the efficiency of photocatalysis are predominantly centered on controllable modulation of anisotropic spatial charge separation/transfer and regulating vectorial charge transport pathways in photoredox catalysis, yet it still meets with limited success. Herein, we first conceptually demonstrate the rational design of unidirectional cascade charge transfer channels over transition metal chalcogenide nanosheets (TMC NSs: ZnIn2S4, CdS, CdIn2S4, and In2S3), which is synergistically enabled by a solid-state non-conjugated polymer, i.e., poly(diallyldimethyl ammonium chloride) (PDDA), and MXene quantum dots (MQDs). In such elaborately designed photosystems, an ultrathin PDDA layer functions as an intermediate charge transport mediator to relay the directional electron transfer from TMC NSs to MQDs that serve as the ultimate electron traps, resulting in a considerably boosted charge separation/migration efficiency. The suitable energy level alignment between TMC NSs and MQDs, concurrent electron-withdrawing capabilities of the ultrathin PDDA interim layer and MQDs, and the charge transport cascade endow the self-assembled TMC/PDDA/MQD heterostructured photosystems with conspicuously improved photoactivities toward anaerobic selective reduction of nitroaromatics to amino derivatives and photocatalytic hydrogen evolution under visible light irradiation. Furthermore, we ascertain that this concept of constructing a charge transfer cascade in such TMC-insulating polymer-MQD photosystems is universal. Our work would afford novel insights into smart design of spatial vectorial charge transport pathways by precise interface modulation via non-conjugated polymers for solar energy conversion.

Boosting Cascade Electron Transfer for Highly Efficient CO2 Photoreduction

Artificial photosynthesis converting carbon dioxide into chemical fuels with a high added value is a promising solution to both fossil fuel shortage/pollution and global climate change; however, the development of highly efficient photocatalysts toward this goal is still largely bereft of fresh ideas. Herein, we propose a “cascade electron transfer” strategy through spurring both interfacial and inner electron transfer rates for a 0D/2D photocatalyst of CsPbBr3/CuTCPP metal organic framework (MOF). Upon photoexcitation, the heterojunction structure with an appropriate band alignment facilitates an ultrafast interfacial electron transfer rate of 1.4 ps from CsPbBr3 segment to CuTCPP MOF and subsequent ultrafast internal electron transfer of 21 ps from CuTCPP ligand to the Cu node within the enlarged 2D framework. The efficient electron transfer ensures efficient charge separation favorable for photocatalytic reactions: The photocatalyst exhibits an outstanding yield of 47.2 μmol g−1 h−1 (CO and CH4 combined) superior to previous reports. Rational design of hierarchical heterojunctions with matching electronic bandgap not only expedites cascade charge transfer but also prevents holes from recombining with electrons or oxidizing the photocatalysts without the necessity of sacrificial reagents. This work thus provides useful insight for boosting photocatalytic efficacy from a dynamic perspective.

Tungsten oxide quantum dots deposited onto ultrathin CdIn2S4 nanosheets for efficient S-scheme photocatalytic CO2 reduction via cascade charge transfer

A novel S-scheme photocatalytic heterojunction composite nanomaterial is developed by integrating zero-dimensional WO3 quantum dots (WQDs) on two-dimensional ultrathin CdIn2S4 (CIS) nanosheets with the aim of fostering carrier separation, enhancing the performance of carrier interface transport, minimizing carrier distance transport, and achieving effective photocatalytic CO2 reduction. The composite photocatalyst WQDs/CdIn2S4 (WCIS) allows for the efficient photocatalytic reduction of CO2 to CO and CH4, as shown by product analysis and isotopic measurement. The photogenerated electrons in WQDs recombine with the holes in CIS nanosheets, and the left electrons in CIS have stronger CO2 reduction abilities. The highest yields of CO and CH4 achieved with the WCIS photocatalyst are 8.2 and 1.6 μmol g-1h−1 ––2.6 and 8 times higher than those for CIS, respectively. Moreover, the S-scheme WCIS possesses a stable crystal structure and recycling ability. Finally, the S-scheme charge transfer path on the WCIS composite is proposed according to theoretical calculation, in-situ irradiated X-ray photoelectron spectroscopy, and electron paramagnetic resonance (ESR) analyses.

Intercalating ultrathin polymer interim layer for charge transfer cascade towards solar-powered selective organic transformation

Transition metal chalcogenide quantum dots (TMCs QDs) constitute a crucial sector of semiconductors on account of large absorption coefficient for light harvesting, peculiar quantum confinement effect, and abundant active sites stemming from ultra-small size. However, elaborate and tunable modulation of anisotropic photoinduced charge carriers over TMCs QDs represents an enduring challenge in terms of sluggish charge transfer kinetic and ultra-short charge lifetime compared with nanoparticulate counterparts, thereby rendering maneuvering charge transfer of TMCs QDs a tough issue. We herein conceptually unlock the unanticipated charge transport capability of solid-state non-conductive poly(diallyl dimethylammonium chloride) (PDDA) for constructing cascade charge transfer pathway over self-assembled wide bandgap semiconductors (WBS)/PDDA/TMCs QDs multilayered heterostructures, by which unidirectional and accelerated electron transfer from TMCs QDs to WBS support mediums was spontaneously activated, markedly boosting the charge separation/migration efficiency. The integrated roles of such ultrathin insulating PDDA intermediate layer as simultaneous surface charge modifying agent and interfacial charge transfer mediator have been evidenced to be universal. The unexpected electron-withdrawing capability of ultrathin PDDA layer endows WBS (SnO2, TiO2)@PDDA@TMCs (CdSe, CdS) QDs heterostructures with significantly enhanced net efficiency of photoactivities toward selective anaerobic reduction of nitroaromatics to amino derivatives under visible light irradiation. Our work would feature a promising scope for rational design of multifarious novel insulating polymers-based photosystems for solar energy conversion.

Porphyrin Conjugated Polymer Grafted onto BiVO4 Nanosheets for Efficient Z‐Scheme Overall Water Splitting via Cascade Charge Transfer and Single‐Atom Catalytic Sites

AbstractThis work shows a novel artificial Z‐scheme photosystem based on a heterometallic Zn‐/Pt‐porphyrin conjugated polymer (ZnPtP‐CP) grafted onto ultrathin BiVO4 nanosheets via Zn–O–V bridging bonds for high‐efficiency overall water photosplitting. An impressive apparent quantum yield of 9.85% at λ = 400 nm is achieved over the resulting ZnPtP–CP/BiVO4 composite, in which BiVO4 nanosheets are in close contact with ZnPtP‐CP nanosheets via Zn–O–V bridging bonds to promote a Z‐scheme charge transfer mechanism with ZnPtP‐CP serving as electron‐rich unit and BiVO4 as hole‐rich one. The photoexcited electrons of BiVO4 transfer to the interface and recombine with the photogenerated holes of ZnPtP‐CP through the Zn–O–V bonds, and thus the strong reducibility of the photoinduced electrons in ZnPtP‐CP and the strong oxidation ability of the photogenerated holes in BiVO4 are maintained. Moreover, the highly dispersed Pt centers (PtN4) in Pt‐porphyrin bridging units act as single‐atom catalytic sites to facilitate a cascade charge transfer by fast migration of the photogenerated electrons from Zn‐porphyrin to Pt‐porphyrin units for the water reduction reaction. This Z‐scheme mechanism with two‐step excitation and cascade charge transfer pathway makes the composite acting as Z‐scheme dual‐function photocatalyst responsible for the efficient solar‐driven overall water photosplitting without the aid of a sacrificial reagent or external bias.