This study provides a significant enhancement in CO2 photoconversion efficiency by the functionalization of a reduced graphene oxide/cadmium sulfide composite (rGO/CdS) with amine. The amine-functionalized graphene/CdS composite (AG/CdS) was obtained in two steps. First, graphene oxide (GO) was selectively deposited via electrostatic interaction with CdS nanoparticles modified with 3-aminopropyltriethoxysilane. Subsequently, ethylenediamine (NH2C2H4NH2) was grafted by an N,N′-dicyclohexylcarbodiimide coupling reaction between the amine group of ethylenediamine and the carboxylic group of GO. As a result, a few layers of amine-functionalized graphene wrapped CdS uniformly, forming a large interfacial area. Under visible light, the photocurrent through the AG/CdS significantly increased because of enhanced charge separation in CdS. The CO2 adsorption capacity on AG/CdS was 4 times greater than that on rGO/CdS at 1 bar. These effects resulted in a methane formation rate of 2.84 μmol/(g h) under visible light and CO2 at 1 bar, corresponding to 3.5 times that observed for rGO/CdS. Interestingly, a high methane formation rate (1.62 μmol/(g h)) was observed for AG/CdS under CO2 at low pressure (0.1 bar), corresponding to a value 20 times greater than that observed for the rGO/CdS. Thus, the enhanced performance for photocatalytic reduction of CO2 on the AG/CdS is due to the improved CO2 adsorption related to the amine groups on amine-functionalized graphene, which sustains the strong absorption of visible light and superior charge-transfer properties in comparison with those of graphene.

In this work, we prepared 90 nm thick TiCT-graphene oxide (GO) membranes laminated on a porous support by mixing GO with TiCT. This process was chosen to prevent the penetration of target molecules through inter-edge defects or voids with poor packing. The lattice period of the prepared membrane was 14.28 Å, as being swelled with water, resulting in an effective interlayer spacing of around 5 Å, which corresponds to two layers of water molecules. The composite membranes effectively rejected dye molecules with hydrated radii above 5 Å, as well as positively charged dye molecules, during pressure-driven filtration at 5 bar. Rejection rates were 68% for methyl red, 99.5% for methylene blue, 93.5% for rose Bengal, and 100% for brilliant blue (hydrated radii of 4.87, 5.04, 5.88, and 7.98 Å, respectively). Additionally, the rejections of composite membrane were compared with GO membrane and TiCT membrane.

Cuprous oxide (Cu2O) is one of the most promising materials for photoreduction of CO2 because of its high conduction band and small band gap, which enable the production of high-potential electrons under visible-light irradiation. However, it is difficult to reduce the CO2 using a Cu2O-based photocatalyst due to fast charge recombination and low photostability. In this work, we enhanced the photocatalytic CO2 conversion activity of Cu2O by hybridization of Cu2O NWAs, carbon layers, and BiVO4 nanoparticles. By construction of a Z-scheme charge flow on a 3-D NWA structure, the BiVO4/carbon-coated Cu2O (BVO/C/Cu2O) NWAs show significantly enhanced charge separation and light harvesting property. As a result, CO formation rate of BVO/C/Cu2O was 9.4 and 4.7 times those of Cu2O mesh and Cu2O NWAs, respectively, under visible light irradiation. In addition, the material retained 98% of its initial photocatalytic CO2 conversion performance after five reaction cycles (20 h) because of the protective carbon layer and Z-schematic charge flow. We believe that this work provides a promising photocatalyst system that combines a 3-D NWA structure and a Z-scheme charge flow for efficient and stable CO2 conversion.

Use of Cu and Cu+ is one of the most promising approaches for the production of C2 products by the electrocatalytic CO2 reduction reaction (CO2RR) because it can facilitate CO2 activation and CC dimerization. However, the selective electrosynthesis of C2+ products on Cu0Cu+ interfaces is critically limited due to the low electrocatalytic production of ethanol relative to ethylene. In this study, a novel porous Cu/Cu2O aerogel network is introduced to afford high ethanol productivity by the electrocatalytic CO2RR. The aerogel is synthesized by a simple chemical redox reaction of a precursor and a reducing agent. CO2RR results reveal that the Cu/Cu2O aerogel produces ethanol as the major product, exhibiting a Faradaic efficiency (FEEtOH) of 41.2% and a partial current density (JEtOH) of 32.55 mA cm−2 in an H‐cell reactor. This is the best electrosynthesis performance for ethanol production reported thus far. Electron microscopy and electrochemical analysis results reveal that this dramatic increase in the electrosynthesis performance for ethanol can be attributed to a large number of Cu0Cu+ interfaces and an increase of the local pH in the confined porous aerogel network structure with a high‐surface‐area.