Intrinsic Charge Polarization in Bi19 S27 Cl3 Nanorods Promotes Selective CC Coupling Reaction during Photoreduction of CO2 to Ethanol

Obtaining multi-carbon products via CO₂  photoreduction is a major catalytic challenge involving multielectron-mediated CC bond formation. Complex design of multicomponent interfaces that are exploited to achieve this chemical transformation, often leads to untraceable deleterious changes in the interfacial chemical environment affecting CO₂  conversion efficiency and product selectivity. Alternatively, robust metal centers having asymmetric charge distribution can effectuate CC coupling reaction through the stabilization of intermediates, for desired product selectivity. However, generating inherent charge distribution in a single component catalyst is a difficult material design challenge. Here, a novel photocatalyst, Bi₁₉ S₂₇ Cl₃ , is presented which selectively converts CO₂  to a C₂  product, ethanol, in high yield under visible light irradiation. Structural analysis through transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveals the presence of charge polarized bismuth centers in Bi₁₉ S₂₇ Cl₃ . The intrinsic electric field induced by charge polarized bismuth centers renders better separation efficiency of photogenerated electron-hole pair. Furthermore, charge polarized centers yield better adsorption of CO* intermediate and accelerate the rate determining CC coupling step through the formation of OCCOH intermediate. Formation of these intermediates is experimentally mapped by in situ Fourier-transform infrared spectroscopy and further confirmed by theoretical calculation.

Synergistic effect of cyano defects and CaCO3 in graphitic carbon nitride nanosheets for efficient visible-light-driven photocatalytic NO removal

Photo-oxidation with semiconductor photocatalysts provides a sustainable and green solution for NO_x elimination. Nevertheless, the utilization of traditional photocatalysts in efficient and safe photocatalytic NO_x removal is still a challenge due to the slow charge kinetic process and insufficient optical absorption. In this paper, we report a novel porous g-C₃N₄ nanosheet photocatalyst modified with cyano defects and CaCO₃ (xCa-CN). The best performing sample (0.5Ca-CN) exhibits an enhanced photo-oxidation NO removal rate (51.18 %) under visible light irradiation, largely surpassing the value of pristine g-C₃N₄ nanosheets (34.05 %). Such an enhancement is mainly derived from an extended visible-light response, improved electron excitation and transfer, which are associated with the synergy of cyano defects and CaCO₃, as evidenced by a series of spectroscopic analyses. More importantly, in-situ DRIFTS and density functional theory (DFT) results suggest that the introduction of cyano defects and CaCO₃ enables control over NO adsorption and activation processes, making it possible to implement a preference pathway (NO → NO⁺ → NO₃¯) and reduce the emission of toxic intermediate NO₂. This work demonstrates the potential of integrating defect engineering and insulator modification to design highly efficient g-C₃N₄-based photocatalysts for air purification.

2D-2D heterostructure g-C3N4-based materials for photocatalytic H2 evolution: Progress and perspectives

Photocatalytic hydrogen generation from direct water splitting is recognized as a progressive and renewable energy producer. The secret to understanding this phenomenon is discovering an efficient photocatalyst that preferably uses sunlight energy. Two-dimensional (2D) graphitic carbon nitride (g-C₃N₄)-based materials are promising for photocatalytic water splitting due to special characteristics such as appropriate band gap, visible light active, ultra-high specific surface area, and abundantly exposed active sites. However, the inadequate photocatalytic activity of pure 2D layered g-C₃N₄-based materials is a massive challenge due to the quick recombination between photogenerated holes and electrons. Creating 2D heterogeneous photocatalysts is a cost-effective strategy for clean and renewable hydrogen production on a larger scale. The 2D g-C₃N₄-based heterostructure with the combined merits of each 2D component, which facilitate the rapid charge separation through the heterojunction effect on photocatalyst, has been evidenced to be very effective in enhancing the photocatalytic performance. To further improve the photocatalytic efficiency, the development of novel 2D g-C₃N₄-based heterostructure photocatalysts is critical. This mini-review covers the fundamental concepts, recent advancements, and applications in photocatalytic hydrogen production. Furthermore, the challenges and perspectives on 2D g-C₃N₄-based heterostructure photocatalysts demonstrate the future direction toward sustainability.

The mesoscale mechanism of P-dopant defects and interface synergy for phenols degradation

The semiconductor based photocatalysis has become a hot spot of current research, and the key challenges are the construction of strong functional heterojunction photocatalysts, and insights on the working mechanism involved. In this work, we constructed a NiFe- LDHs/P-TCN heterojunction with P-dopant defects and interface synergy, and elucidated its mesoscale mechanism among different constituent interfaces. The interface photoelectron transfer was detected by PAS, EPR and other methods, and the enhancing mechanism of the defect sites for interface electron transfer and photocatalytic activity was proposed. The interfacial electrons, photoelectric properties and photocatalytic activity are found to be positively correlated. The result is conducive for a better understanding on working mechanism of heterogeneous photocatalysts, which opened up a broader research space for the rational design and construction of functional interfaces.

Modulating Carrier Transfer over Carbazolic Conjugated Microporous Polymers via Donor Structural Design for Functionalization of Thiophenols

Developing photocatalysts to steer conversion of solar energy toward high-value-added fine chemicals represents a potentially viable approach to address the energy crisis and environmental issues. However, enablement of this conversion is usually impeded by the sluggish kinetic process for proton-coupled electron transfer and rapid recombination of photogenerated excitons. Herein, we report a simple and general structural expansion strategy to facilitate charge transfer in conjugated microporous polymers (CMPs) via engineering the donor surrounding the trifluoromethylphenyl core. The resulting CMPs combine high surface area, strong light-harvesting capabilities, and tunable optical properties endowed by extended π-conjugation; the optimized compound CbzCMP-5 generated from 9,9',9″-(2-(trifluoromethyl)benzene-1,3,5-triyl)tris(9H-carbazole) remarkably enhanced the photogenerated carrier transfer efficiency, enabling the functionalization of thiophenols toward thiocarbamates and 3-sulfenylindoles with high photocatalytic efficiency. Most importantly, the in-depth insights into the carrier-transfer processes open up new prospects on further optimization and rational design of photoactive polymers for efficient charge-transfer-mediated reactions.

Tribocatalytic degradation of dyes by tungsten bronze ferroelectric Ba2.5Sr2.5Nb8Ta2O30 submicron particles

Searching for a new approach in environmental remediation in terms of dye degradation is important in industrialized society. In this work, ferroelectric Ba2.5Sr2.5Nb8Ta2O30 (BSNT) submicron powders prepared by the high-temperature solid-phase method are used for dye degradation under magnetic stirring. The dye in solution can be quickly degraded by magnetically stirring BSNT submicron particles in the dark in ambient temperature conditions. More importantly, the degradation efficiency can be greatly improved through simple modification of the stirring materials from glass to polypropylene, with a degradation efficiency of rhodamine B as high as 99% in 1.5 h at a gentle stirring speed of 300 rpm. Control experiments reveal that the degradation of the dye is mainly contributed by the friction between BSNT submicron particles and PTFE stirring rods. It is proposed that the friction between ferroelectric polar BSNT particles and PTFE causes charge transfer and induces a non-zero internal electric field to drive the separation of electron-hole pairs in BSNT particles, resulting in a novel tribocatalytic degradation of the dye, which is proven by the detection of ˙OH and ˙O2 - intermediate products during stirring. This work demonstrates that the friction energy of ferroelectric materials with strong polarization is an alternative approach for highly efficient dye degradation.

Self-grown oxygen vacancies-rich CeO2/BiOBr Z-scheme heterojunction decorated with rGO as charge transfer channel for enhanced photocatalytic oxidation of elemental mercury

Oxygen vacancy-rich CeO₂/BiOBr was prepared via solvothermal method combined with rGO to design a Z-scheme heterojunction, which was used for photocatalytic oxidation of gaseous elemental mercury. The Z-scheme heterojunction constructed by interface engineering significantly promotes charge carriers transfer at the interface. Moreover, the surface oxygen vacancies and Ce³⁺/Ce⁴⁺ redox centers tend to capture electrons to accelerate the Z-scheme path of charge transfer to maintain efficient redox performance and facilitate molecular oxygen activation to boost photocatalytic removal of Hg⁰. The collaboration of oxygen vacancies, Ce³⁺/Ce⁴⁺ and heterojunction enhances the photocatalytic oxidation activity, which achieves a removal efficiency of 76.53%, which is 1.29 times that of BiOBr and 1.91 times that of CeO₂. The effect of actual flue gas components (SO₂, NO and HCl) on the performance of photocatalytic Hg⁰ removal was further investigated. Combined with DFT theoretical calculations, the photocatalytic reaction mechanism of Z-scheme heterojunction with oxygen vacancies-rich was proposed. It provides a feasible strategy for the development of high-efficiency Z-scheme heterojunction photocatalytic system for environmental purification.