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Carbon-based quantum dots (QDs), as a new type of zero-dimensional (0D) inorganic material, are favored by researchers because of their superior optical properties, good water solubility, and biocompatibility. Besides graphene QDs (GQDs), many new carbon-based QD materials with good quality and excellent performance have emerged in recent years, such as g-C3N4 QDs (CNQDs), MXene QDs (MQDs), and graphdiyne QDs (GDQDs). These carbon-based QDs will open up unprecedented new opportunities in the fields of materials science, energy and environmental photocatalysis. Regrettably, a comprehensive review of the relevant topics is lacking. This review focuses on the applications of emerging carbon-based QD materials in sustainable photocatalysis. Herein, the structural characteristics of carbon-based QDs are first depicted. On this basis, the preparation, modification, and photocatalytic mechanism of high-quality carbon-based QDs are comprehensively summarized. Subsequently, the latest research progress on typical carbon-based QDs in the field of sustainable photocatalysis is discussed categorically. Finally, the future developments and challenges of highly active carbon-based QDs are proposed insightfully. This review is expected to provide powerful scientific guidance for the design, fabrication, and application of carbon-based QD materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Tricobalt tetroxide (Co 3 O 4) has been developed as a promising photocatalyst material for various applications. Several reports have been published on the self-modification of Co 3 O 4 to achieve optimal photocatalytic performance. The pristine Co 3 O 4 alone is inadequate for photocatalysis due to the rapid recombination process of photogenerated (PG) charge carriers. The modification of Co 3 O 4 can be extended through the introduction of doping elements, incorporation of supporting materials, surface functionalization, metal loading, and combination with other photocatalysts. The addition of doping elements and support materials may enhance the photocatalysis process, although these modifications have a slight effect on decreasing the recombination process of PG charge carriers. On the other hand, combining Co 3 O 4 with other semiconductors results in a different PG charge carrier mechanism, leading to a decrease in the recombination process and an increase in photocatalytic activity. Therefore, this work discusses recent modifications of Co 3 O 4 and their effects on its photocatalytic performance. Additionally, the modification effects, such as enhanced surface area, generation of oxygen vacancies, tuning the band gap, and formation of heterojunctions, are reviewed to demonstrate the feasibility of separating PG charge carriers. Finally, the formation and mechanism of these modification effects are also reviewed based on theoretical and experimental approaches to validate their formation and the transfer process of charge carriers. [ABSTRACT FROM AUTHOR]

To date, the piezoelectric field has been demonstrated as a promising approach to inhibit the recombination of photogenerated carrier in photocatalyst applications. Herein we propose a MoS 2 /Bi 4 O 5 Br 2 /PVDF-HFP piezo-photocatalytic film in the organic pollutants remediation. MoS 2 /Bi 4 O 5 Br 2 as the photocatalytic material is incorporated to poly (vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) as the supporting layer via a simple phase transition method. The polarised electric field generated on PVDF-HFP and MoS 2 /Bi 4 O 5 Br 2 under aeration synergised with the built-in electric field formed between MoS 2 /Bi 4 O 5 Br 2 Z-scheme heterojunction to promote the interfacial charge transfer. The degradation rates of rhodamine B (RhB) and tetracycline hydrochloride (TC) under aeration and visible light irradiation in 60 min reached 98.9% and 92.2%, respectively. Meanwhile, density functional theory calculations (DFT) further demonstrated the effective charge separation and transfer induced by the Z-scheme charge transfer mechanism constructed by MoS 2 composite with Bi 4 O 5 Br 2 , as well as the synergistic effect of the double electric field in favour of suppressing carrier recombination. This work provides an interesting solution for effectively combining piezoelectric catalysis with photocatalysis. [Display omitted] • MoS 2 /Bi 4 O 5 Br 2 forms a Z-scheme heterojunction that retains a high redox capacity. • Piezoelectric field and built-in electric field synergistically enhance photocatalytic performance. • Utilizing aeration as the driving force to generate the piezoelectric effect is simple and energy efficient. • DFT calculations confirm the double electric field effect of the photocatalytic system. [ABSTRACT FROM AUTHOR]

The construction of high-quality graphitic carbon nitride (g-C 3 N 4 )-based heterojunctions remains a grand challenge. Herein, the ternary heterojunctions of g-C 3 N 4 /ZnS/CuS has been fabricated via a facile three-step process: the polymerization of melamine, the loading of ZnS nanoparticles (NPs), and further deposition of hexagonal CuS nanosheets. Compared with pure g-C 3 N 4 , there is an extended visible-light absorption over 500–800 nm for g-C 3 N 4 /ZnS/CuS, which enables the possible utilization of low-energy visible light. Moreover, ZnS NPs interface layers and hexagonal CuS nano-sheets can be both utilized as electron co-catalysts to markedly improve the separation efficiency of the photo-generated electrons and holes and decrease interface transfer resistance, resulting in highly efficient photocatalytic activity for degradation of Rhodamine B (RhB) and significantly enhanced photoconductivity in an all-solid-state device. This work can be helpful for developing other effective hetero-structured photocatalysts and photoelectrical devices. [ABSTRACT FROM AUTHOR]

The rational fabrication of an efficient photocatalyst with optimal interface engineering remains a huge challenge for the enhancement of photocatalytic perpformance. Herein, a sequence of multidimensional nanocomposites with different spatial interfaces, including point, and line or face-contact surface are controllable designed by horizontal growing diverse dimensional (0D, 1D,2D and 3D) copper sulfide (CuS) on 2D graphitic-carbon nitride (g-C 3 N 4) nanosheets. Physical and photochemical measurements demonstrate that the formation of an extraordinary 2D/2D face-to-face contact interface can not only enhance the specific surface area, visible light utilization, and photo-excited charge separation efficiency, but also elevate the density and lifetime of photo-generated carriers. The results of ultraviolet photoemission spectroscopy (UPS) and density functional theory (DFT) calculation also confirm that charge transfer tends to occur in face-to-face contact. Among the types of nanocomposites considered, 2D/2D g-C 3 N 4 /CuS has the smallest electron transfer barrier (Ф Be) between active species, thereby displaying the maximum photocatalytic apparent rate constant, which is about 12 times larger than that of pristine g-C 3 N 4. Most importantly, this work systematically investigates the relationship between microscopic interface structure and photocatalytic activity from the perspective of the optical, and electrical and energy levels, providing a new insight on the rational design of desired interface engineering towards efficient photocatalysts. [Display omitted] • 2D/xD g-C3N4/CuS nanocomposites with different spatial interfaces were fabricated. • 2D/2D g-C3N4/CuS nanocomposite displays the optimal photocatalytic performance. • The concentration, lifetime and separation-efficiency of photogenerated carriers were tested. • The energy barrier between active species and catalysts was analyzed by UPS and DFT. • The photocatalytic mechanism of 2D/2D g-C3N4/CuS nanocomposites is proposed. [ABSTRACT FROM AUTHOR]