Construction of an Ultrathin S‐Scheme Heterojunction Based on Few‐Layer g‐C₃N₄ and Monolayer Ti₃C₂T_x MXene for Photocatalytic CO₂ Reduction

Abstract

As charge carriers transfer is critical for the photocatalytic activity enhancement of step‐scheme (S‐scheme) photocatalysts, facile construction of a S‐scheme heterojunction with great contact area and strong interaction between the compositions is highly desirable. Herein, an ultrathin S‐scheme heterojunction g‐C3N4/TiO2/C (SL‐EAC) consisting of few‐layer g‐C3N4 nanosheets on monolayer Ti3C2Tx MXene converted TiO2/C is prepared through an electrostatic self‐assembly and calcination method. The monolayer Ti3C2Tx can not only prevent g‐C3N4 from agglomerating through forming close contact with g‐C3N4, but its conversion to TiO2/C during calcination can build a bridge between the relatively inert TiO2 and multigroup‐terminated Ti3C2Tx, which indirectly enhances the interface contact between TiO2/C and g‐C3N4. SL‐EAC with a thickness of around 5 nm shows much better photocatalytic CO2 reduction performance than g‐C3N4, TiO2/C prepared by calcination of monolayer Ti3C2Tx and g‐C3N4/TiO2/C (EAC) prepared by the same method but monolayer Ti3C2Tx is altered by multilayer Ti3C2Tx. The excellent performance of SL‐EAC is attributed to the large contact area between g‐C3N4 and TiO2/C, which is conducive to the S‐scheme transfer of photogenerated charge carriers. Moreover, the samples prepared using different methods are also investigated, which further confirms the great contact area and strong interaction between the composites in ultrathin SL‐EAC.

S‐Scheme Photocatalytic Systems

“…Therefore, numerous S‐scheme photocatalysts for CO 2 reduction have been explored, e.g., g‐C 3 N 4 /Cu 3 P|S, g‐C 3 N 4 /Ti 3 C 2 T x Mxene, ZnMn 2 O 4 /ZnO, CdS/TiO 2 , g‐C 3 N 4 /CdSe‐DETA, g‐C 3 N 4 /Bi/BiVO 4 , g‐C 3 N 4 /Bi 12 O 17 C l2 , SnNb 2 O 6 /CdSe, TiO 2 @PDA, and BP/g‐C 3 N 4 . [ 61–71 ] Deng et al constructed hierarchical S‐scheme ZnMn 2 O 4 /ZnO nanofiber photocatalysts with using electrospinning and subsequent calcination. [ 62 ] The S‐scheme heterojunction photocatalysts present more than 4 times increment in CO and CH 4 products than pure ZnO nanofiber photocatalysts.…”

In Situ Constructed P–N Junction on Cu2O Nanocubes through Reticular Chemistry for Simultaneously Boosting CO2 Reduction Depth and Ameliorating Photocorrosion

“…The prolonged τ av of the latter further attests to the improved photocarrier separation, and thus the higher probability of photogenerated electrons and holes in participating the redox reactions. [ 46–48 ]…”

Recent Progress of Perovskite Oxide in Emerging Photocatalysis Landscape: Water Splitting, CO₂ Reduction, and N₂ Fixation

“…As one of our main energy sources, fossil fuels have indeed accelerated the process of human community development, while carbon dioxide became the main greenhouse gas at the same time [163][164][165][166][167][168] . In recent years, the inexorable rise of carbon dioxide level in the atmosphere has already exceeded 400 × 10 −6 and the concentration of CO2 has increased at a rate higher than that of 2 × 10 −6 every year, highlighting the need for reducing the present CO2 emissions [168][169][170][171][172][173] . Therefore, the production of valuable chemicals or fuels using the greenhouse gas, CO2 as a carbon source has been considered as a promising solution in dealing with the critical issues of energy shortages, clean energy production, and maintaining the normal carbon cycle to get the global environment back on track 169,[174][175][176][177][178][179][180][181][182] .…”