N-doped C dot/CoAl-layered double hydroxide/g-C3N4 hybrid composites for efficient and selective solar-driven conversion of CO2 into CH4

Converting CO 2 into value-added fuel by utilizing abundant solar energy could in principle minimize fossil fuel consumption and anthropogenic CO 2 emissions. However, developing catalytic systems with high selectivity and efficiency is necessary for photocatalytic CO 2 conversion. Here we report the fabrication of a N-doped C dot/CoAl-layered double hydroxide/g-C 3N 4 (NCD/LDH/CN) hybrid heterojunction photocatalyst for high efficiency and selectivity reduction of CO 2 with water into CH 4 under simulated-solar-light illumination. The NCD/LDH/CN hybrid photocatalyst demonstrated remarkable CH 4 production with an optimum rate of 25.69 μmol g −1 h −1, an apparent quantum yield of 0.62%, and 99% selectivity for CH 4. This NCD/LDH/CN hybrid system also exhibited exceptional stability and durability during consecutive test cycles with no apparent change in activity. The high activity and stability of the NCD/LDH/CN hybrid toward CO 2 photoreduction is essentially attributable to the strong synergy among the NCD, LDH, and CN constituents, which hinder charge recombination by accelerating charge transportation processes, together with the favorable properties such as broad optical response and good CO 2 adsorption capability. We explored the role of the NCDs in the NCD/LDH/CN hybrid system as a metal-free co-catalyst for the efficient and selective production of CH 4 from CO 2 photoreduction. Thus, the present report provides new insights into the rational fabrication of noble-metal-free photocatalysts for efficient and selective sustainable hydrocarbon production from photocatalytic reduction of CO 2. </p

G-C3N4 (2D)/CdS (1D)/rGO (2D) dual-interface nano-composite for excellent and stable visible light photocatalytic hydrogen generation

A 2D/1D/2D dual-interface nano-composite configuration in the form of CdS nanorods sandwiched between g-C3N4 and rGO sheets with intimate interfacial contact is synthesized by a facile wet-chemical method and is shown to exhibit excellent photocatalytic H2 generation under visible-light irradiation. In particular, the optimal g-C3N4/CdS/rGO dual-interface nano-composite shows H2 production rate of ∼4800 μmol h-1 g-1, which is almost 44, 11 and 2.5 times higher than that shown by pure g-C3N4 nanosheets, and the g-C3N4/rGO and g-C3N4/CdS single interface heterostructures, respectively. It is shown that the synergic effects involving the band structure match and close interfacial contact, which can accelerate the separation and transfer of photoinduced charge carriers, and the enhanced visible-light absorption together contribute to the impressive photocatalytic performance and photostability of the g-C3N4/CdS/rGO ternary nano-composite system. Specific advantages of a dual-interface triple-composite system over a single interface case(s) are also brought out

g-C3N4/ NiAl-LDH 2D/2D Hybrid Heterojunction for High-Performance Photocatalytic Reduction of CO2 into Renewable Fuels

2D/2D interface heterostructures of g-C3N4 and NiAl-LDH are synthesized utilizing strong electrostatic interactions between positively charged 2D NiAl-LDH sheets and negatively charged 2D g-C3N4 nanosheets. This new 2D/2D interface heterojunction showed remarkable performance for photocatalytic CO2 reduction to produce renewable fuels such as CO and H2 under visible-light irradiation, far superior to that of either single phase g-C3N4 or NiAl-LDH nanosheets. The enhancement of photocatalytic activity could be attributed mainly to the excellent interfacial contact at the heterojunction of g-C3N4/NiAl-LDH, which subsequently results in suppressed recombination, and improved transfer and separation of photogenerated charge carriers. In addition, the optimal g-C3N4/NiAl-LDH nanocomposite possessed high photostability after successive experimental runs with no obvious change in the production of CO from CO2 reduction. Our findings regarding the design, fabrication and photophysical properties of 2D/2D heterostructure systems may find use in other photocatalytic applications including H2 production and water purification

Construction of Bi₂WO₆/RGO/g-C₃N₄ 2D/2D/2D hybrid Z-scheme heterojunctions with large interfacial contact area for efficient charge separation and high-performance photoreduction of CO₂ and H₂O into solar fuels

We have rationally constructed a hybrid heterojunction comprising of Bi2WO6, reduced graphene oxide, and g-C3N4 (BWO/RGO/CN) with a 2D/2D/2D configuration for efficient photoreduction to generate solar fuels. These heterojunctions displayed dramatically improved performance towards CO2 reduction to generate CO and CH4 under visible-light irradiation, compared to the base material (CN), P25 as reference, as well as binary BWO/CN and RGO/CN heterojunctions. Particularly, the BWO/RGO/CN heterojunctions with 1 wt. % RGO and 15 wt. % BWO achieved record performance in the yields of carbonaceous products (CO + CH4) compared to other synthesized catalysts, with a selectivity of 92% against H2. The remarkable photocatalytic performance was mainly attributed to the unique 2D/2D/2D architecture that creates large interfacial contact between the constituent materials for rapid charge transfer, to hinder the direct recombination of photoinduced electrons and holes. Notably, RGO played two significant roles: as a supporter to capture the electrons from CN, and as a redox mediator to promote the Z-scheme charge transfer between CN and BWO. The result is a greater extent of charge separation in the present BWO/RGO/CN heterojunction system, as evidenced by the photoluminescence, photocurrent responses, and electron microscopy findings. More importantly, the heterojunctions displayed excellent stability during recycling tests with no obvious loss in the generation of CO and CH4 from photoreduction of CO2. This interesting interfacial engineering approach presented herein offers a promising route for the rational design of a new class of layered multicomponent heterojunctions with 2D/2D/2D architecture for various applications in environmental protection and solar energy conversion.</p

In situ phase transformation synthesis of unique Janus Ag2O/Ag2CO3 heterojunction photocatalyst with improved photocatalytic properties

Herein, Ag2O/Ag2CO3 nanocomposite with unique Janus morphology was synthesized by a facile ion-exchange followed by an in situ phase transformation method with precise control of its nucleation and growth processes. Contrary to conventional synthetic procedures of Janus architectures, the present Janus system was constructed without the need for surfactants or toxic chemicals. Most importantly, the visible-light-absorbing Janus Ag2O/Ag2CO3 nanocomposite exhibits a remarkable performance toward the degradation of Rhodamine B and 4-chlorophenol, far superior to that observed for bare Ag2CO3. The obvious enhancement of the photocatalytic performance of this nanocomposite is mainly attributed to the intimate Ag2O/Ag2CO3 interface created by its exceptional Janus architecture, which in turn allows for rapid charge transfer processes. Additionally, the Janus system exhibited a high photostability during recycling experiments with no significant change in the degradation activity

g‑C₃N₄/NiAl-LDH 2D/2D Hybrid Heterojunction for High-Performance Photocatalytic Reduction of CO₂ into Renewable Fuels

2D/2D interface heterostructures of g-C₃N₄ and NiAl-LDH are synthesized utilizing strong electrostatic interactions between positively charged 2D NiAl-LDH sheets and negatively charged 2D g-C₃N₄ nanosheets. This new 2D/2D interface heterojunction showed remarkable performance for photocatalytic CO₂ reduction to produce renewable fuels such as CO and H₂ under visible-light irradiation, far superior to that of either single phase g-C₃N₄ or NiAl-LDH nanosheets. The enhancement of photocatalytic activity could be attributed mainly to the excellent interfacial contact at the heterojunction of g-C₃N₄/NiAl-LDH, which subsequently results in suppressed recombination, and improved transfer and separation of photogenerated charge carriers. In addition, the optimal g-C₃N₄/NiAl-LDH nanocomposite possessed high photostability after successive experimental runs with no obvious change in the production of CO from CO₂ reduction. Our findings regarding the design, fabrication and photophysical properties of 2D/2D heterostructure systems may find use in other photocatalytic applications including H₂ production and water purification

Defective nano-silica loaded polymeric carbon nitride for visible light driven CO2 reduction and dye degradation

A hybrid composite of polymeric carbon nitride (PCN) and defective nano-silica (n-SiOx) photocatalyst has been synthesized, exhibiting a high surface area, improved light response, and reduced charge recombination. The synergistic formation of PCN-n-SiOx interface facilitated photoinduced charge transfer from PCN to n-SiOx, resulting in suppressed carrier recombination. The resultant hybrid PCN-n-SiOx sample demonstrated a three-fold photocatalytic reduction of CO2 into methanol and formic acid. Furthermore, photoelectrocatalytic CO2 reduction selectively yielded 283.0 μmol L−1 of formic acid, a five-fold increment compared to bare PCN (57.0 μmol L−1). These findings hold promise for the development of PCN-based hybrid composites for solar-powered applications