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Polymers are usually restricted on the high exciton binding energies and sluggish electron transfer because of the low dielectric constants. Regulating spin-polarized electrons is regarded as an attractive strategy, but often confined to the d-orbital elements. Here, the nonmetal P and N elements co-mediated the spin polarization of carbon nitrides (PCN) have been elaborately designed. The optimized PCN-3 shows an outstanding hydrogen production (22.2 mmol·g−1·h−1) coupled with selective benzylamine oxidation without using any solvent and cocatalysts, which is 200 times of original C3N4 and superior to the photocatalysts has been reported to date. Experimental and theoretical results verified that the spin-orbital coupling of N 2p and P 2p remarkably increased the parallel spin states of charge and reduced the formation of singlet excitons to accelerate exciton dissociation in carbon nitride. In addition, charge separation and surface catalysis can be significantly enhanced by the electron spin polarization of carbon nitride with the parallel arrangement, huge built-in electric field and disturbed electronic structure. Our finding deepens the insight into the charge separation and exciton dissociation in spin polarization, and offers new tactics to develop high-efficiency catalysts. [ABSTRACT FROM AUTHOR]

The establishment of heterojunctions between phase interfaces is an important strategy to enhance catalytic activity, but the behavior of charge transfer and exciton dissociation is unsharpness and significant. Here, a Van der Waals heterojunction (VDWH) of Mo 2 C/Bi 4 O 5 Br 2 composite with oxygen vacancies (BM) was synthesized via a facile method. Various experimental results and density functional theory calculations demonstrated that the compact VDWH and unsaturated oxygen vacancy induced interfacial Mo-O bonds to modulate surface electronic structure. Consequently, the electron extracted from the exciton formed a strong internal electric field, which boosted the dissociation of the excitons and charge transfer via the electron transfer channel of the Mo-O bond. Therefore, the BM shows excellent CO 2 reduction performance (1277.4 µmol g−1 h−1) and stability without using sacrificial agents and cocatalysts, which is about 6 times of Mo 2 C/Bi 4 O 5 Br 2. This work not only gives deep insights into charge separation in VWDH and oxygen vacancy but also provides an efficient photocatalyst for efficient green energy conversion. [Display omitted] • The Bi 4 O 5 Br 2 and Mo 2 C VDWH with oxygen-rich defects was prepared by the self-assembly method. • The interfacial Mo-O bonds for modulating surface electronic structure. • The Mo-O bonds could boost the excitons dissociation and charge transfer. • BM materials exhibited excellent photocatalytic activity and stability. [ABSTRACT FROM AUTHOR]

Poly(heptazine imide) as a metal-free semiconductor has stimulated considerable focus in the photocatalytic nitrogen fixation. However, the weak visible light absorption and unordered migration of photogenerated carriers as well as limited active site often resulted in poor photocatalytic performance. Here, we propose a conceptual to construct directional electron delivery channel via introducing C-N and N-C-O units linked terminal melem units (PCON) using a facile copolymerizing method. The optimized PCON achieved excellent photocatalytic nitrogen fixation rate (49.11 μmol g−1 h−1) and near-IR yield in pure water without using cocatalyst, which is 11 times higher than that of pristine C 3 N 4. Based on DFT calculation and experiment results, the superior photocatalytic performance is traced back to the integrated different linker into the framework induced n − π * transitions and acted as charge channel and activation site, which could significantly extend light absorption to the near IR, and enhance charge separation as well as reactive activation. This study lay out the importance of linker engineer of the catalyst to regulate photocatalytic activity over organic-based photocatalysts. [Display omitted] • A facile strategy to construct directional electron delivery channel using a facile copolymerizing method. • Different linker species act as charge channel and activation site. • It achieved excellent photocatalytic nitrogen fixation rate and stability. • A considerable NH 3 production could be obtained under 750 nm monochromatic light illumination. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile strategy has been developed to construct the polarity-bridged PDI composite. • The embled polarity bridges enlarged the built-in electric fields. • The polarity bridges promoted carriers transfer and exciton dissociation. • BOPDI shows excellent photocatalytic activity and stability. Constructing acceptor–donor units (D/A) of polymer is an efficient method for promoting carrier separation to optimize photoreactivity. However, the carriers across the D/A interface of micromolecule was relatively hindered by the Coulomb potential. In this work, the polarity-bridged acceptor–donor units of perylene-3,4,9,10-tetracarboxylic acid diimide (PDI) composite (BOPDI) has been constructed using a simple strategy. The improved BOPDI achieves excellent photocatalytic nitrogen fixation rate (74.0 μmol g−1h−1) as well as stability without using any co-catalyst and sacrificial agent, which is 11 times that of the original PDI group. DFT calculations and experimental results show that the polarity-bridges reasonably adjusts the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) bands and absorption characteristics, ensuring the BOPDI absorbed near-infrared light and activated N 2 molecules. In addition, the polarity bridged units strengthen the construction of the built-in electric field for overcoming the Coulomb potential, resulting in a higher carrier separation and exciton dissociation efficiency. This work not only provides a tactics for enhancing the electronic transmission of D/A units, but also expanding the application research of PDI composite materials in the photocatalytic reduction of nitrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • First report of bismuth ion-containing N/S Coordination based metallopolymer photocatalyst. • The Bi-N bond is beneficial for oxygen absorption and separation of charge carriers. • It shows high photocatalytic activity and stability in selective oxidation of styrene using air. Photocatalytic selective oxidation organic compounds to produce high additional value of products with air hold great promising in the chemical industry, but the photocatalyst often suffered from serious recombination of charge carriers, limited conversion efficiency, poor oxygen adsorption and stability. Here, a novel bismuth complexes with N/S coordination based metallopolymer (BiTMT) has been prepared by a facile wet-chemical method. It is confirmed that the weak interaction of Bi−N bonds not only acted as electron trapping site and charge bridge to facilitate the separation of photogenerated charge carrier, but also played an important role in the adsorption and activation of oxygen from air. BiTMT exhibits excellent conversion efficiency and stability in the selective oxidation of styrene using air as oxidant under visible light irradiation. This finding opens an avenue to design functional sites for photocatalytic selective oxidation and other applications. [ABSTRACT FROM AUTHOR]