A Universal Strategy for Boosting Hydrogen Evolution Activity of Polymer Photocatalysts under Visible Light by Inserting a Narrow‐Band‐Gap Spacer between Donor and Acceptor

Abstract

It is challenging for polymer photocatalysts to achieve high photocatalytic performance under visible light due to their weak light absorption in visible light region. Herein, a universal strategy for boosting the photocatalytic activity of donor-acceptor (D-A) conjugated polymer photocatalysts upon visible light irradiation by inserting a π-spacer of thiophene unit between the electron donors and acceptors to form a D-π-A molecular structure is reported. The introduction of thiophene unit with narrow band gap can enhance the conjugation degree of the polymer chains and extend the light absorption range. Meanwhile, the introduction of thiophene spacer through ternary copolymerization also enables the controllability on the chemical structure of the resulting D-π-A polymers by altering the feed ratio between the electron donors and acceptors. The optimized D-π-A copolymer photocatalyst shows an impressive hydrogen evolution rate (HER) of 78.4 mmol h -1 g -1 under visible light irradiation, and the HER could be further improved to 127.9 mmol h -1 g -1 under UV-vis light irradiation by loading 1 wt% Pt co-catalyst. More importantly, this strategy can also be extended to other polymeric photocatalysts with different donor and acceptor units, demonstrating the universality for enhancing the photocatalytic activity of polymeric photocatalysts.

An Efficient Electron Donor for Conjugated Microporous Polymer Photocatalysts with High Photocatalytic Hydrogen Evolution Activity

“…This high HER value of 126.81 mmol h -1 g -1 is comparable with that of the reported polymer photocatalysts with high photocatalytic activity (Table S1, Supporting Information). For example, the linear polymer TP-BTDO-2 comprising of multi-thiophene and BTDO units showed a HER of 161.28 mmol h -1 g -1 with 1 wt% Pt under UV-Vis light, [17] the linear polymer PBDTTS-1SO exhibited a HER of 97.1 mmol h -1 g -1 under the assistance of 3 wt% Pt and irradiation of 380-780 nm light, [33] the copolymer Py-T-BTDO-3 consisting of pyrene, BTDO and thiophene showed a HER of 127.9 mmol h -1 g -1 under UV-Vis light by loading 1 wt% Pt cocatalyst, [29] the thiophene and pyrene based CP-St polymer demonstrated a high HER of 303.7 mmol h -1 g -1…”

“…Based on the developed D-A polymer photo catalysts to date, [15,[19][20][21][22] dibenzo[b,d]thiophene-S,S-dioxide (BTDO) might be the most effective acceptor unit due to its strong electronwithdrawing capability and high hydrophilicity, [23][24][25] and pyrene with planar molecular structure and large delocalized π-electron system is the most effective electron donor to prepare high performance polymer photocatalysts. [26,27] Although there have been significant advances in the photo catalytic activity of polymer photocatalysts by structure optimization, [28,29] the limited scope of high efficient electron donors and acceptors hinders the further development of organic polymer photo catalysts. To further improve the photocatalytic activity and enrich the D-A) molecular structure show high photocatalytic activity for hydrogen evolution due to the efficient light-induced electron/hole separation, which is mostly determined by the nature of electron donor and acceptor units.…”

Arylboron functional covalent organic frameworks for synergistic photocatalytic hydrogen evolution

“…6,7 To solve these problems, Yanagida 8 and Wang 1 successively reported organic materials poly( p -phenylene) and carbon nitride (g-C 3 N 4 ) as photocatalysts and verified their photocatalytic HER ability, respectively. Subsequently, more organic polymers were explored as photocatalysts for the HER, including the carbon nitride (g-C 3 N 4 ) family, 1 conjugated microporous polymers (CMPs), 9 covalent triazine-based frameworks (CTFs), 10 conjugated linear polymers (CLPs), 11 and others. 12,13 However, photocatalytic HER is a multi-step continuous process that requires comprehensive regulation of molecular mechanisms with respect to the light-harvesting capability, band gap, and interface to reduce photo-generated electron/hole recombination.…”

Reaction Pathways toward Sustainable Photosynthesis of Hydrogen Peroxide by Polymer Photocatalysts

“…Hence, both thermodynamic and kinetic factors influence the H 2 O 2 production yield. Until now, various approaches such as creating heterojunctions, extending light absorption ranges, depositing spatially separated cocatalysts, tuning surface properties, and improving charge separation have been developed to enhance the SCC efficiency. ,,,,,,− Taking these strategies together to design a high-efficiency polymer photocatalyst is practically infeasible. Thus, the reported SCC efficiency is still far from the requirements for industrial applications.…”