Construction of a ZnIn₂S₄/Au/CdS Tandem Heterojunction for Highly Efficient CO₂ Photoreduction

Abstract

Photocatalytic CO 2 reduction technology is of great importance to alleviate energy crisis and environmental pollution; however, it remains a serious challenge due to the fast recombination of carriers. In this study, we report a three-dimensional structure of a ZnIn 2 S 4 /Au/CdS composite photocatalyst for the CO 2 reduction reaction, where Au nanoparticles (NPs) are evenly anchored on the surface of ZnIn 2 S 4 by photodeposition and Au NPs are wrapped around by CdS. In ZnIn 2 S 4 /Au/CdS composite photocatalysts, Au NPs act as a bridge to construct a "semiconductor−metal−semiconductor" tandem electron transfer mechanism (ZnIn 2 S 4 → Au → CdS) heterojunction, which greatly promotes the transfer of photogenerated electrons. It is worth noting that Au NPs, as a local surface plasmon resonance (LSPR) effect excited source to generate excited-state electrons, further improve the photoreduction CO 2 activity. Under UV−vis light irradiation, the CO yield of ZnIn 2 S 4 /Au/CdS can reach 63.07 μmol•g −1 •h −1 , which is higher than that of 6.37 μmol•g −1 •h −1 for pure ZnIn 2 S 4 , 0.93 μmol•g −1 •h −1 for CdS, 8.9 μmol•g −1 •h −1 for ZnIn 2 S 4 /CdS, 31.04 μmol•g −1 •h −1 for ZnIn 2 S 4 /Au, and 5.37 μmol•g −1 •h −1 for CdS/Au. In addition, the ternary ZnIn 2 S 4 /Au/CdS composite photocatalyst has good cyclic stability. This study broadens the idea of designing photocatalysts with good carrier separation efficiency.

Combing Hollow Shell Structure and Z-Scheme Heterojunction Construction for Promoting CO2 Photoreduction

“…As shown in Figure e and Figure S16, the peaks at 1246.5 cm –1 , 1429.5 cm –1 , and 1367.5 cm –1 are attributed to HCO 3 – and m-CO 3 2– adsorbed on CdS, respectively. These results confirm the adsorption of CO 2 on the CdS surface in the form of monodentate carbonate. − Significantly, the peaks located at 1148 cm –1 and in the range 1500–1550 cm –1 correspond to *COOH adsorbed on the CdS surface, − and the peak located at 2076 cm –1 corresponds to *CO, (Figure S17) which is the key intermediate for CO 2 photoreduction to produce CO. , The in-situ DRIFT peak intensity of CdS/Au/DHCZ corresponding to *COOH enhanced obviously after light irradiation, providing strong evidence for photocatalytic CO 2 hydrogenation. Subsequently, *COOH will be further hydrogenated and dehydrated to form CO.…”

Oxygen-Doped Red Carbon Nitride: Enhanced Charge Separation and Light Absorption for Robust CO2 Photoreduction

“…Moreover, in situ FTIR (Figure d) was conducted, and the results could give a more in-depth insight into the photoreduction CO 2 process over the O–CN. The peaks at 1313, 1445, and 1611 cm –1 could be assigned to CO 2 – , symmetric stretches of bidentate carbonate (b-CO 3 2– ) groups, and the monodentate carbonate (m-CO 3 2– ) groups. , The peaks around 1552 and 1721 cm –1 were designated to the COOH* intermediate. The COOH* is produced when CO 2 * molecules react with the photogenerated protons.…”

“…The results suggested that CO 2 molecules bind more firmly on the ) groups. 27,28 The peaks around 1552 and 1721 cm −1 were designated to the COOH* intermediate. The COOH* is produced when CO 2 * molecules react with the photogenerated protons.…”

Solar CO2 Reduction Enabled by Cascade Hole Migration

“…2,46 Notably, water also plays an important role in this route by following the route H 2 O + CO 2 → H 2 CO 3 → HCO 3 − + H + → CO 3 2− + H + according to the intermediates detected by DRIFTS. 41 On the other hand, according to the DRS (Figure 1d) and M−S (Figure 4d) results, CB and VB positions of CIS are identified as −0.64 and 1.63 V (vs NHE), respectively. The redox potential of CO 2 −CO relative to NHE (E 0 redox [vs NHE]) is located at −0.53 V vs NHE.…”

“…39,40 Moreover, the peaks at 1679 and 1261 cm −1 are corresponding to the • CO 2 − species. 19,37,41 Overall, different carbonate species correspond to the carbonic acid and/or the adsorbed CO 2 on the catalyst surface. 42 The appearance of peak at 1749 and 1633 cm −1 belong to the *COOH species, which correspond to the typical intermediate of CO 2 -to-CO conversion.…”