Effective Low-Powered Photocatalytic Disinfection via Synchronous Introduction of Oxygen Dopants and Carbon Defects in Carbon Nitride.

Establishing an effective metal-free photocatalyst for sustainable applications remains a huge challenge. Herein, we developed ultrathin oxygen-doped g-C3N4 nanosheets with carbon defects (OCvN) photocatalyst via a facile gas bubble template-assisted thermal copolymerization method. A series of OCvN with different dopant amounts ranging from 0 to 10% were synthesized and used as photocatalysts under illumination of low-power (2 × 18 W, 0.18 mW/cm2) and commercially available energy-saving light bulbs. Upon testing for photocatalytic Escherichia coli inactivation, the best-performing sample, OCvN-3, demonstrated an astonishing disinfection activity of over 7-log reduction after 3 h of illumination, boasting an 18-fold improvement in its antibacterial activity compared to that of pristine g-C3N4. The enhanced performance was attributed to the synergistic effects of increased surface area, extended visible light harvesting, improved electronic conductivity, and ultralow resistance to charge transfer. This study successfully introduced a green photocatalyst that demonstrates the most effective disinfection performance ever recorded among metal-free g-C3N4 materials. Its disinfection capabilities are comparable to those of metal-based photocatalysts when they are exposed to low-power light.

Self-activated superhydrophilic green ZnIn2S4 realizing solar-driven overall water splitting: close-to-unity stability for a full daytime.

Engineering an efficient semiconductor to sustainably produce green hydrogen via solar-driven water splitting is one of the cutting-edge strategies for carbon-neutral energy ecosystem. Herein, a superhydrophilic green hollow ZnIn2S4 (gZIS) was fabricated to realize unassisted photocatalytic overall water splitting. The hollow hierarchical framework benefits exposure of intrinsically active facets and activates inert basal planes. The superhydrophilic nature of gZIS promotes intense surface water molecule interactions. The presence of vacancies within gZIS facilitates photon energy utilization and charge transfer. Systematic theoretical computations signify the defect-induced charge redistribution of gZIS enhancing water activation and reducing surface kinetic barriers. Ultimately, the gZIS could drive photocatalytic pure water splitting by retaining close-to-unity stability for a full daytime reaction with performance comparable to other complex sulfide-based materials. This work reports a self-activated, single-component cocatalyst-free gZIS with great exploration value, potentially providing a state-of-the-art design and innovative aperture for efficient solar-driven hydrogen production to achieve carbon-neutrality.

Elucidating the enhanced decomposition of alkyl hydroperoxides on oxygen vacancy rich TiO2-x surfaces using DFT for polyethylene decomposition.

Effective photocatalytic polyethylene degradation by TiO2 is hindered by the sluggish kinetics of alkyl hydroperoxide decomposition. Introduction of oxygen vacancies onto TiO2 destabilizes the hydroperoxide O-O bond due to mid-gap states and the elevated Fermi level. Downshift of the d-band center by oxygen vacancies also enhanced adsorbate-surface interactions and lowered the activation energy barrier from Gibbs calculations. Experimental evidence additionally substantiated enhanced polyethylene degradation on TiO2-x compared to TiO2.

Point-Defect Engineering: Leveraging Imperfections in Graphitic Carbon Nitride (g-C3 N4 ) Photocatalysts toward Artificial Photosynthesis.

Graphitic carbon nitride (g-C3 N4 ) is a kind of ideal metal-free photocatalysts for artificial photosynthesis. At present, pristine g-C3 N4 suffers from small specific surface area, poor light absorption at longer wavelengths, low charge migration rate, and a high recombination rate of photogenerated electron-hole pairs, which significantly limit its performance. Among a myriad of modification strategies, point-defect engineering, namely tunable vacancies and dopant introduction, is capable of harnessing the superb structural, textural, optical, and electronic properties of g-C3 N4 to acquire an ameliorated photocatalytic activity. In view of the burgeoning development in this pacey field, a timely review on the state-of-the-art advancement of point-defect engineering of g-C3 N4 is of vital significance to advance the solar energy conversion. Particularly, insights into the intriguing roles of point defects, the synthesis, characterizations, and the systematic control of point defects, as well as the versatile application of defective g-C3 N4 -based nanomaterials toward photocatalytic water splitting, carbon dioxide reduction and nitrogen fixation will be presented in detail. Lastly, this review will conclude with a balanced perspective on the technical and scientific hindrances and future prospects. Overall, it is envisioned that this review will open a new frontier to uncover novel functionalities of defective g-C3 N4 -based nanostructures in energy catalysis.

Rational Design of Carbon-Based 2D Nanostructures for Enhanced Photocatalytic CO2 Reduction: A Dimensionality Perspective.

Photocatalytic CO2 reduction is a revolutionary approach to solve imminent energy and environmental issues by replicating the ingenuity of nature. The past decade has witnessed an impetus in the rise of two-dimensional (2D) structure materials as advanced nanomaterials to boost photocatalytic activities. In particular, the use of 2D carbon-based materials is deemed as highly favorable, not only as a green material choice, but also due to their exceptional physicochemical and electrical properties. This Review article presents a diverse range of alterations and compositions derived from 2D carbon-based nanomaterials, mainly graphene and graphitic carbon nitride (g-C3 N4 ), which have remarkably ameliorated the photocatalytic CO2 performance. Herein, the rational design of the photocatalyst systems with consideration of the aspect of dimensionality and the resultant heterostructures at the interface are systematically analyzed to elucidate an insightful perspective on this pacey subject. Finally, a conclusion and outlook on the limitations and prospects of the cutting-edge research field are highlighted.

Z-Scheme Photocatalytic Systems for Solar Water Splitting.

As the world decides on the next giant step for the renewable energy revolution, scientists have begun to reinforce their headlong dives into the exploitation of solar energy. Hitherto, numerous attempts are made to imitate the natural photosynthesis of plants by converting solar energy into chemical fuels which resembles the "Z-scheme" process. A recreation of this system is witnessed in artificial Z-scheme photocatalytic water splitting to generate hydrogen (H2). This work outlines the recent significant implication of the Z-scheme system in photocatalytic water splitting, particularly in the role of electron mediator and the key factors that improve the photocatalytic performance. The Review begins with the fundamental rationales in Z-scheme water splitting, followed by a survey on the development roadmap of three different generations of Z-scheme system: 1) PS-A/D-PS (first generation), 2) PS-C-PS (second generation), and 3) PS-PS (third generation). Focus is also placed on the scaling up of the "leaf-to-tree" challenge of Z-scheme water splitting system, which is also known as Z-scheme photocatalyst sheet. A detailed investigation of the Z-scheme system for achieving H2 evolution from past to present accompanied with in-depth discussion on the key challenges in the area of Z-scheme photocatalytic water splitting are provided.