Nano Ag‐Decorated MoS₂ Nanosheets from 1T to 2H Phase Conversion for Photocatalytically Reducing CO₂ to Methanol

Abstract

Exfoliated MoS2 with a 2H phase has unique semiconductor properties and is used for the photocatalytic reduction of CO2 herein. Flower‐like MoS2 nanosheets are synthesized by the hydrothermal method and are used to fabricate an enlarged lamellar structure with a 1T phase of MoS2 in the presence of lithium ions under sonication; the 1T‐to‐2H phase conversion of MoS2 is successfully realized in o‐dichlorobenzene solution. To improve the photocatalytic performance, Ag nanoparticles are combined with the as‐prepared 2H‐MoS2 to form the Schottky knot. The obtained Ag/2H‐MoS2 composites are characterized and evaluated for their compositions, morphologies, microstructures, and photocatalytic activities in the reduction of CO2 to methanol. Herein, it was found that the electron and hole excited by light on the composites are more effectively separated through deposited nano Ag, and their photocatalytic ability of reducing CO2 to methanol is promoted simultaneously. The highest yield of methanol up to 365.08 μmol−1 g−1 h−1 appears at 20 wt% Ag on MoS2. Finally, a reasonable photocatalytic reaction mechanism is proposed.

Molybdenum‐based heterogeneous catalysts for the control of environmental pollutants

“…Moreover, the band gap of MoS 2 can be adjusted by controlling the number of layers, enhancing the potential for further manipulation 19 . Normally, modification strategies for CO 2 photoreduction consist of constructing Z‐scheme or heterojunctions to strengthen charge separation, 157,158 loading noble metals for strengthened light adsorption, 159 establishing special morphology to modulate CO 2 adsorption and products desorption 19 and combining aforementioned strategies.…”

Engineering approach toward catalyst design for solar photocatalytic CO 2 reduction: A critical review

“…As not all the semiconductors possess the active sites for CO 2 adsorption, doping co‐catalysts is thus necessary to modulate the electronic structure. Up to now, various dopants including both metal elements (ie, Ag, Mo, Cu, Fe, Co, and In) and non‐metal elements (ie, C, F, V, P, and B) have been reported as active sites for photoreduction of CO 2 30,55,59,91‐93 . Zhang's group has incorporated Ag nanoparticles into the 2H‐MoS 2 to form the Schottky junction for enhancing the photocatalytic performance 55 .…”

“…Up to now, various dopants including both metal elements (ie, Ag, Mo, Cu, Fe, Co, and In) and non‐metal elements (ie, C, F, V, P, and B) have been reported as active sites for photoreduction of CO 2 30,55,59,91‐93 . Zhang's group has incorporated Ag nanoparticles into the 2H‐MoS 2 to form the Schottky junction for enhancing the photocatalytic performance 55 . It turns out that Ag nanoparticles not only hinder the recombination of electrons and holes, but also serve as the active sites for converting CO 2 to methanol with the highest productivity of 365.08 μmol h −1 g −1 .…”

“…For example, TiO 2 has been considered as one of the most popular semiconductors applied to photocatalysis with prestigious advantages, including easy availability, low toxicity, outstanding chemical stability, and unique optical and electronic properties, and a recently published review on TiO 2 ‐based photocatalysts for CO 2 reduction is available 54 . Nevertheless, because of inefficient solar energy utilization substantiated by the wide bandgap, researchers have employed various methods to improve the activity of such photocatalysts, including metal or non‐metal doping, 40,41,55‐61 alloying, 42,51‐53 facet engineering, 62‐65 nanostructure tailoring, 13,40,46,66,67 surface defect engineering, 43,68,69 and p‐n heterojunction or Z‐scheme system constructing 44,45,47‐50,70‐74 . In general, these methods all aim at either improving the separation efficiency of photogenerated electron/hole pairs, namely prolonging the lifespan of electrons for CO 2 reduction, or creating more catalytically active sites.…”

Transition Metal Dichalcogenides for the Application of Pollution Reduction: A Review

“…Direct conversion of CO 2 to high-value chemicals (such as intermediate chemicals, fuels, and alcohols) has a high potential for commercial value [269,270]. TMDCs have demonstrated properties for catalyzing CO 2 into important alcohol, especially methanol [85,271]. Bolivar et al [272] studied the use of a Pt/MoO x /MoSe 2 electrocatalyst and proposed that oxygen-containing surface species lowers the electric potential for methanol production.…”