Enhancing the photocatalytic properties of PbS QD solids: the ligand exchange approach

Abstract

Surface engineering of nanomaterials is a promising tool towards the design of new materials for conversion of solar energy into chemical energy.

Sensitization of SnO2 Single Crystals with Multidentate‐Ligand‐Capped PbS Colloid Quantum Dots to Enhance the Photocurrent Stability

“…The 4f 7/2 peak was fit with two components centered at 137.8 eV and 138.8 eV. The former corresponds to the binding energy of Pb−S bonds, and the latter is assigned to Pb(OH) 2 or PbSO 3 , which matches with other studies with 3‐MPA and EDT . However, the DMSA capped PbS QDs has a much smaller peak ratio of 138.8 eV to 137.8 eV compared to 3‐MPA and EDT, and for the sulfur 2p both lead sulfite (PbSO 3 ) and lead sulfate (PbSO 4 ) peaks are not observed, which both indicates that DMSA capped PbS QDs are possibly more stable and oxidation resistive compared to the ones capped with 3‐MPA and EDT.…”

“…By using the integrated peak areas shown in Table 2, where the Pb 4f 7/2 and S 2p 3/2 are used to calculate the S: Pb ratio, which is 0.927, relatively close to the unity. [60] The XPS result confirms the success of ligand exchange and also provides an insight that DMSA may be more stable and oxidation resistive compared with 3-MPA and EDT. However, a more comprehensive XPS study with sensitized SnO 2 is needed to draw a firm conclusion that DMSA has more stable QDs -SnO 2 interaction than traditional bifunctional ligands and PbI ligand.…”

“…However, the DMSA capped PbS QDs has a much smaller peak ratio of 138.8 eV to 137.8 eV compared to 3‐MPA and EDT, and for the sulfur 2p both lead sulfite (PbSO 3 ) and lead sulfate (PbSO 4 ) peaks are not observed, which both indicates that DMSA capped PbS QDs are possibly more stable and oxidation resistive compared to the ones capped with 3‐MPA and EDT. By using the integrated peak areas shown in Table , where the Pb 4f 7/2 and S 2p 3/2 are used to calculate the S: Pb ratio, which is 0.927, relatively close to the unity . The XPS result confirms the success of ligand exchange and also provides an insight that DMSA may be more stable and oxidation resistive compared with 3‐MPA and EDT.…”

“…As shown in Figure 5a, the sulfur 2p peaks at 160.85 eV and 161.95 eV correspond to the binding energy of PbÀ S at 2p 3/2 and 2p 1/2 respectively, that are same as reported in the literature. [60][61][62] Sulfur 2p peaks at 163.6 eV and 164.7 eV correspond to free thiol groups CÀ SÀ H, [41,63] indicating free thiol groups from DMSA, that are not bound to Pb. Similar results are also reported in EDT capped PbS quantum dots by Sargent et al and Moreels et al [61,62] The 2p 3/2 peak areas for PbS and thiol group are presented in Table 1, where the calculated free…”

“…The former corresponds to the binding energy of PbÀ S bonds, and the latter is assigned to Pb(OH) 2 or PbSO 3 , which matches with other studies with 3-MPA and EDT. [30,[60][61][62] However, the DMSA capped PbS QDs has a much smaller peak ratio of 138.8 eV to 137.8 eV compared to 3-MPA and EDT, and for the sulfur 2p both lead sulfite (PbSO 3 ) and lead sulfate (PbSO 4 ) peaks are not observed, which both indicates that DMSA capped PbS QDs are possibly more stable and oxidation resistive compared to the ones capped with 3-MPA and EDT. By using the integrated peak areas shown in Table 2, where the Pb 4f 7/2 and S 2p 3/2 are used to calculate the S: Pb ratio, which is 0.927, relatively close to the unity.…”