Reduced graphene oxide supported C₃N₄ nanoflakes and quantum dots as metal-free catalysts for visible light assisted CO₂ reduction

Abstract

The visible light photocatalytic reduction of CO2 to fuel is crucial for the sustainable development of energy resources. In our present work, we report the synthesis of novel reduced graphene oxide (rGO)-supported C3N4 nanoflake (NF) and quantum dot (QD) hybrid materials (GCN) for visible light induced reduction of CO2. The C3N4 NFs and QDs are prepared by acid treatment of C3N4 nanosheets followed by ultrasonication and hydrothermal heating at 130–190 °C for 5−20 h. It is observed that hydrothermal exposure of acid-treated graphitic carbon nitride (g-C3N4) nanosheets at low temperature generated larger NFs, whereas QDs are formed at higher temperatures. The formation of GCN hybrid materials was confirmed by powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy (TEM), and UV–vis spectroscopy. High-resolution TEM images clearly show that C3N4 QDs (average diameter of 2–3 nm) and NFs (≈20–45 nm) are distributed on the rGO surface within the GCN hybrid material. Among the as-prepared GCN hybrid materials, GCN-5 QDs exhibit excellent CO2 reductive activity for the generation of formaldehyde, HCHO (10.3 mmol h−1 g−1). Therefore, utilization of metal-free carbon-based GCN hybrid materials could be very promising for CO2 photoreduction because of their excellent activity and environmental sustainability.

Design and engineering of graphene nanostructures as independent solar-driven photocatalysts for emerging applications in the field of energy and environment

“…150 The rGO-supported C 3 N 4 nanoflake and quantum dot hybrid materials could reduce CO 2 into HCHO under visible light irradiation. 151 Other than being the substrate, GO could also serve as the electron mediator to connect CsPbBr 3 and α-Fe 2 O 3 to form an all-solid-state Z-scheme system to photocatalytically reduce CO 2 to CO. 152 The hybridization of the metal complex molecule and graphene materials was also confirmed to be effective to promote the photocatalytic performance of CO 2 reduction. Ma et al linked Co quaterpyridine complexes to carboxylic acid groups functionalized graphene surfaces.…”

Recent Progress on Carbon Nitride and Its Hybrid Photocatalysts for CO2 Reduction

“…For instance, g‐C 3 N 4 quantum dots (CNQD, 0D) have been synthesized and coordinated with various materials to prepare hybrid catalysts. [ 34,35 ] Zheng et al prepared CNQDs via dialysis by molecular porous membrane and loaded CNQDs on ultrathin 2D Co porphyrin MOF to fabricate an excellent hybrid catalyst for photocatalytic CO 2 RR. [ 34 ] There are plenty of N atoms in CNQD that can form a direct and intimate bridge with active Co sites, enhancing CO 2 adsorption capacity and promoting photogenerated charges transfer from CNQDs to Co sites.…”

Role of excited-state hydrogen bonding in CO2 photoreduction catalyzed by sodium magnesium chlorophyll

“…1 Photoreduction of CO 2 is a promising way to reduce CO 2 emissions by converting CO 2 into valuable energyrich carbon products, which is an effective strategy for us to solve environmental and energy problems. The key point in photoreduction of CO 2 is catalytic materials, and the photocatalytic materials commonly used in current research are multiphase catalysts such as metal oxides, nonmetallic materials, metal-organic frameworks (MOFs), semiconductor quantum dots, single-atom catalysts, [2][3][4] and homogeneous catalysts (soluble metal complexes, soluble metal porphyrins, 5-7 etc.). There have been several recent reports of experimental and computational studies of the CO 2 RR.…”