Enhanced Photocatalytic Hydrogen Evolution from Organic Ternary Heterojunction Nanoparticles Featuring a Compact Alloy‐Like Phase

Abstract

Organic semiconductor nanoparticles (NPs) are attractive photocatalysts to produce hydrogen from water splitting. Herein, a ternary strategy of incorporating crystalline n-type molecule IDMIC-4F into the host system made of p-type polymer PM6 and n-type molecule ITCC-M is demonstrated. ITCC-M and IDMIC-4F form compact alloy-like composite with shorter lattice spacing in the ternary p/n heterojunction NPs, resulting in enhanced exciton dissociation and charge transfer characteristics. As the result, an unprecedented hydrogen evolution rate (HER) of 307 mmol h −1 g −1 and a maximum apparent quantum efficiency of 5.9% at 600 nm are achieved in the optimized ternary NPs (PM6:ITCC-M:IDMIC-4F = 1:1.3:0.2), which is among the highest HER from organic photocatalysts to the best of the authors' knowledge. The alloylike composite also improves the operational stability of ternary NP photocatalysts. This study shows that synergizing two compatible n-type small molecules to form alloy-like composite is a promising approach to design novel organic photocatalysts for boosting the photocatalytic hydrogen evolution efficiency.

Emerging Light‐Harvesting Materials Based on Organic Photovoltaic D/A Heterojunctions for Efficient Photocatalytic Water Splitting

“…[16c,22] Recently, Liu et al constructed a binary and ternary heterojunction, named PM6/ITCC-M and PM6/ITCC-M/IDMIC-4F, respectively (Figure 5a). [23] The best ternary nanoparticles output a superior hydrogen yield rate of 306 mmol h À 1 g À 1 comparing to that of 260 mmol h À 1 g À 1 for binary ones (Figure 5b). An overall study has disclosed that ITCC-M : IDMIC-4F alloylike composites could be formed inside of ternary nanoparticles and plays an important role in improving HER activities.…”

Emerging Light‐Harvesting Materials Based on Organic Photovoltaic D/A Heterojunctions for Efficient Photocatalytic Water Splitting

“…Hydrogen yield rate (mmol h À 1 g À 1 ) Surfactants [a] PTB7-Th/EH-IDTBR [18] 5 wt % Pt 64.4 TEBS PTB7-Th/EH-IDTBR [18] 5 wt % Pt 3.1 SDS PCDTBT/PC 60 BM [20] 3 wt % Pt 105.2 / PFBT/PFODTBT/ITIC [22] 6 wt % Pt 60.8 PS-PEG-COOH PM6/ITCC-M [23] 10 wt % Pt 260 SDBS PM6/ITCC-M/IDMIC-4F [23] 10 wt % Pt 306 SDBS gIDTBT/oIDTBR [24] 10 wt % Pt 18.5 TEBS PM6/Y6 [25] 10 wt % Pt 43.9 TEBS PM6/PC 71 BM [25] 5 wt % Pt 73.7 TEBS PM6/BTP-4F [26] 15 wt % Pt 64.3 TEBS PM6/BTP-FOH [26] 15 wt % Pt 78.4 TEBS PM6/BTP-2OH [26] 15 wt % Pt 102.1 TEBS PM6/TPP [27] 20 wt % Pt 72.7 TEBS F1 [28] 33 wt % Pt 152.6 TEBS PM6/Y6CO [30] 33 wt % Pt 323.2 TEBS PM6/Y6-R [31] 16 wt % Pt 205 TEBS PM6/Y6-S [31] 16 wt % Pt 217 TEBS PBDB-T/ITIC [32] 10 wt % Pt 257 SDBS POZ-M/ITIC [33] 6 wt % Pt 63 PS-PEG-COOH…”

Molecular Structure Engineering toward Enhanced Photocatalytic Hydrogen Evolution and Stability of Organic Heterojunction Nanoparticles

“…34 PM6 and the SMAs were then assembled into heterojunction NPs through the mini-emulsion method according to our previous work, using amphiphilic sodium dodecyl benzenesulfonate (SDBS) as the surfactant. 12,13 Their optical properties were first probed by absorption and photoluminescence (PL) measurements. As shown in Figure S3a− c, although all three of the SMA-based heterojunction NPs show complementary absorption spectra to PM6, the PM6:IDMIC NPs exhibited an absorption coefficient that is twice as large as that as the PM6:ITIC NPs, and the absorption coefficient for the PM6:IT-4F NPs is quadruple that of the PM6:ITIC NPs.…”

“…Photocatalytic hydrogen (H 2 ) evolution (PHE) converts solar energy into chemical energy through the use of photocatalysts and has attracted widespread attention in recent years due to its potential to produce low-cost, environmentally friendly H 2 . − Different to the routinely used ultraviolet-active (UV-active) inorganic photocatalysts like TiO 2 and WO 3 , − organic photocatalysts based on electron donor/acceptor heterojunctions have high flexibility in their molecular and compositional design. This flexibility allows for tunable optoelectronic properties and the ability to utilize solar energy in a broad wavelength, thus showing promising prospects for PHE. − …”

“…The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acscatal.3c02932.The Experimental Section, the synthesis procedure for IDMIC, details on the fabrication of the heterojunction nanoparticles, an energy level diagram with Y in coordinates E vs NHE, and characterizations including 1 H NMR,13 C NMR, UV−vis, TRPL, DLS, water contact angle studies, and ICP-OES (PDF)…”