Insights into the Photoassisted Electrocatalytic Reduction of CO₂ over a Two‐dimensional MoS₂ Nanostructure Loaded on SnO₂ Nanoparticles

Abstract

Photoelectrochemical reduction of CO2 to value‐added chemicals and fuels is an attractive strategy to store renewable energy and mitigate greenhouse gas emissions. In this study, based on the density functional theory (DFT) calculation, a two‐dimensional nanostructure MoS2 loaded on SnO2 nanoparticles (MS/SON) was prepared for photoassisted electrocatalytic reduction of CO2 to HCOOH through a two‐step process of facile hydrothermal and pyrolysis method. Through physical structure characterization and photoelectric performance test, the results indicated that the 5 % MS/SON exhibits exclusive HCOOH selectivity, the maximum FE is 43.8 %, the current density reached to 9 mA cm−2 at −1.4 V and the photocurrent value is 12.5 μA cm−2 under 0.5 V bias. The overpotential is as low as 245 mV. Besides, after the introduction of MoS2, there is a red shift in the adsorption band edge from 380 nm to 500 nm, indicating an enhancement of light response; the peak intensity of photoluminescence (PL) decreased, showing that the electron and hole are effectively separated; the values of electrochemical impedance spectroscopy (EIS) and Tafel plots (70 mV dec−1) were smaller than other ratios, demonstrating that the faster charge transfer rate; the proper introduction of MoS2 increased the specific surface area from 47.64 m2 g−1 to 55.99 m2 g−1, which was helpful to expand the number of active sites. It is demonstrated that MS/SON is an excellent CO2 reduction material.

Editors’ Choice—Review—Creating Electrocatalytic Heterojunctions for Efficient Photoelectrochemical CO2 Reduction to Chemical Fuels

“…Hu et al examined the photo-assisted electrocatalytic reduction of CO 2 with 2D MoS 2 loaded onto SnO 2 nanoparticles, which are known to be selective toward HCOOH. 78 The study found that a 5% MoS 2 on SnO 2 was ideal for photocatalytic performance for the conversion of CO 2 to HCOOH with a current density of 9.8 mA cm −2 at −1.4 V vs Ag/AgCl and overpotential of 0.245 V vs RHE. The faradaic efficiency for the HCOOH product was also determined to be 43.8% at −0.85 V vs Ag/AgCl in aqueous 0.5 M NaHCO 3 buffer with a photocurrent value of 12.5 μA cm −2 , which implies that the SnO 2 nanoparticles aid in the selectivity and charge separation of the MoS 2 .…”

“…The faradaic efficiency for the HCOOH product was also determined to be 43.8% at −0.85 V vs Ag/AgCl in aqueous 0.5 M NaHCO 3 buffer with a photocurrent value of 12.5 μA cm −2 , which implies that the SnO 2 nanoparticles aid in the selectivity and charge separation of the MoS 2 . 78 Qiao et al studied a p-n heterojunction made with MoS 2 nanosheets and 1D SnO 2 fibers with a low molar ratio of Mo/Sn for use as a 4-nitrophenol reduction catalyst. 79 The heterostructure here showed excellent selectivity to the reduction of 4-nitrophenol with the increased activity being attributed to the hierarchical structure exposing more active sites of the catalyst as well as the p-n junction responsible for efficient charge separation.…”

Two-Dimensional Layered Heterojunctions for Photoelectrocatalysis

“…244 Hu et al investigated MoS 2 nanosheets loaded on SnO 2 nanoparticles as a photocathode. 245 It was discovered that a 5% loading of MoS 2 is the best for increasing the catalytic activity in terms of Faradaic efficiency and current density, with respect to the bare SnO 2 .…”

Toward Excellence in Photocathode Engineering for Photoelectrochemical CO2 Reduction: Design Rationales and Current Progress

“…Several other oxides have been applied for PEC CO 2 RR such as Co 3 O 4 , [ 133,255 ] NiO 2 , [ 256 ] SnO 2 , [ 257 ] etc. Among them, Co 3 O 4 has striked as an appealing choice for oxide materials on account of its suitable bandgap ≈2 eV which spans in the visible range and its exceptionally high selectivity toward formate.…”