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The current bottleneck in the development of efficient photocatalysts for hydrogen evolution is the limited availability of high‐performance acceptor units. Over the past nine years, dibenzo[b,d]thiophene sulfone (DBS) has been the preferred choice for the acceptor unit. Despite extensive exploration of alternative structures as potential replacements for DBS, a superior substitute remains elusive. In this study, a symmetry‐breaking strategy was employed on DBS to develop a novel acceptor unit, BBTT‐1SO. The asymmetric structure of BBTT‐1SO proved beneficial for increasing multiple moment and polarizability. BBTT‐1SO‐containing polymers showed higher efficiencies for hydrogen evolution than their DBS‐containing counterparts by up to 166 %. PBBTT‐1SO exhibited an excellent hydrogen evolution rate (HER) of 222.03 mmol g−1 h−1 and an apparent quantum yield of 27.5 % at 500 nm. Transient spectroscopic studies indicated that the BBTT‐1SO‐based polymers facilitated electron polaron formation, which explains their superior HERs. PBBTT‐1SO also showed 14 % higher HER in natural seawater splitting than that in deionized water splitting. Molecular dynamics simulations highlighted the enhanced water‐PBBTT‐1SO polymer interactions in salt‐containing solutions. This study presents a pioneering example of a substitute acceptor unit for DBS in the construction of high‐performance photocatalysts for hydrogen evolution. [ABSTRACT FROM AUTHOR]

Organic‐conjugated polymer dots (Pdots) are emerging as promising photocatalysts for solar‐driven hydrogen production. However, organic solvents are commonly used as cosolvents in photocatalytic systems to promote the dispersion of organic materials and improve the overall efficiency of the photocatalytic process. Herein, two naphthalenediimide (NDI)‐based Pdots, with and without surfactant, are fabricated and presented as highly efficient and stable photocatalysts for visible‐light‐driven hydrogen generation in a solvent‐free organic system for the first time. The prepared Pdots exhibit high photocatalytic activity and remarkable photostability. Achieving high efficiency and long‐term photostability is essential for the future commercialization of large‐scale hydrogen production. Furthermore, the NDI‐BTF‐PS‐PEG‐COOH Pdots of the dual acceptor (A1‐D‐A2‐D system) consisting of a strong acceptor (NDI, A1) and a weak acceptor (BTF, A2) exhibit high photocatalytic efficiencies and stabilities with Pt‐cocatalyst over 72 h. Thus, constructing A1‐D‐A2‐D NDI‐based Pdots is a promising approach to developing efficient and stable photocatalysts for solar‐driven hydrogen production. [ABSTRACT FROM AUTHOR]

Designing an organic polymer photocatalyst for efficient hydrogen evolution with visible and near-infrared (NIR) light activity is still a major challenge. Unlike the common behavior of gradually increasing the charge recombination while shrinking the bandgap, we present here a series of polymer nanoparticles (Pdots) based on ITIC and BTIC units with different π-linkers between the acceptor-donor-acceptor (A-D-A) repeated moieties of the polymer. These polymers act as an efficient single polymer photocatalyst for H2 evolution under both visible and NIR light, without combining or hybridizing with other materials. Importantly, the difluorothiophene (ThF) π-linker facilitates the charge transfer between acceptors of different repeated moieties (A-D-A-(π-Linker)-A-D-A), leading to the enhancement of charge separation between D and A. As a result, the PITIC-ThF Pdots exhibit superior hydrogen evolution rates of 279 µmol/h and 20.5 µmol/h with visible (>420 nm) and NIR (>780 nm) light irradiation, respectively. Furthermore, PITIC-ThF Pdots exhibit a promising apparent quantum yield (AQY) at 700 nm (4.76%). Designing an organic polymer photocatalyst for efficient hydrogen evolution in the near-infrared (NIR) light region is still a major challenge. The authors present here a series of polymer nanoparticles for a efficient hydrogen evolution under visible and NIR light irradiation, without combining or hybridizing with other materials. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution from natural seawater faces the severe challenges of abundant salts, which adsorb on the active sites and result in undesirable side reactions and photocatalyst poisoning. Herein, a series of main‐chain‐engineered discontinuously conjugated polymer (DCP) photocatalysts is presented with bifunctional crown ether (CE) structures for hydrogen evolution from seawater. The hydrophilic CE can significantly inhibit the aggregation of DCPs induced by salts. Meanwhile, cyclic CE can effectively adsorb cations to uncover the active sites to increase their interaction with protons, which can increase the hydrogen evolution rates and significantly reduce the efficiency roll‐off in natural seawater. Through atomistic studies, the formation of hydrogen bonds with bifunctional CE is elucidated and further analysis of the microscale mechanisms is also conducted using molecular dynamics and ab initio techniques. This work suggests that CE‐based polymer has the potential to enhance its ability to produce hydrogen through photocatalysis using seawater. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting is attracting considerable interest because it enables the conversion of solar energy into hydrogen for use as a zero-emission fuel or chemical feedstock. Herein, we present a universal approach for inserting hydrophilic non-conjugated segments into the main-chain of conjugated polymers to produce a series of discontinuously conjugated polymer photocatalysts. Water can effectively be brought into the interior through these hydrophilic non-conjugated segments, resulting in effective water/polymer interfaces inside the bulk discontinuously conjugated polymers in both thin-film and solution. Discontinuously conjugated polymer with 10 mol% hexaethylene glycol-based hydrophilic segments achieves an apparent quantum yield of 17.82% under 460 nm monochromatic light irradiation in solution and a hydrogen evolution rate of 16.8 mmol m−2 h−1 in thin-film. Molecular dynamics simulations show a trend similar to that in experiments, corroborating that main-chain engineering increases the possibility of a water/polymer interaction. By introducing non-conjugated hydrophilic segments, the effective conjugation length is not altered, allowing discontinuously conjugated polymers to remain efficient photocatalysis. The introduction of hydrophilic segments into the main-chain of polymer photocatalysts allows water to efficiently enter the interior through these hydrophilic segments, and results in effective water/polymer interfaces for hydrogen evolution. [ABSTRACT FROM AUTHOR]

The application of donor-acceptor (D-A) conjugated polymer catalysts for hydrogen evolution reaction (HER) has shown great promise because of the tunability of such catalysts to have desired properties. Herein, we synthesized two polymer catalysts: poly[4,4′-(9-(4-aminophenyl)-9H-carbazole-3,6-diamine-alt-5-oxido-5-phenylbenzo[b]phosphindole-3,7-diyl)dibenzaldehyde] (PCzPO) and poly[N1,N1-bis(4-amino-2-fluorophenyl)-2-fluorobenzene-1,4-diamine-alt-5-oxido-5-phenylbenzo[b]phosphindole-3,7-diyl)dibenzaldehyde] (PNoFPO). The UV-vis absorption spectra showed that the less planar structure and the presence of electronegative fluorine atoms in the donor group of PNoFPO led to a higher optical gap compared to PCzPO, leading to almost five times faster HER rate using PCzPO compared to PNoFPO. However, density functional theory (DFT) calculations show that the frontier orbitals and the highest occupied molecular orbitals – lowest unoccupied molecular orbitals (HOMO-LUMO) gaps of PCzPO and PNoFPO D-A moiety models are very similar, such that, during light absorption, electrons move from donor to acceptor group where proton binding is preferred to happen thereafter. For both PCzPO and PNoFPO D-A moieties, H2 formation through an intramolecular reaction with a barrier of 0.6–0.7 eV, likely occurs at the acceptor group atoms where protons bind through electrostatic interaction. The intermolecular reaction has nearly zero activation energy but is expected to occur only when the repulsion is low between separate polymers chains. Finally, experimental and DFT results reveal the importance of extended configurations of D-A polymers on HER rate. [ABSTRACT FROM AUTHOR]

Efficient polymer photocatalysts that mimic natural photosynthesis to generate H2 through the visible‐light‐promoted splitting of water are ideal systems for the conversion of solar energy into usable fuel with high energy density and in an environmentally friendly manner. In this article, we review recent reports on donor‐acceptor‐based π‐conjugated polymers as photocatalysts, including conjugated linear polymers, microporous polymers, triazine frameworks, covalent organic frameworks, polymer dots, and other related organic polymers, which show superior photocatalytic activity and robust stability under visible‐light irradiation, for hydrogen production. Moreover, their syntheses and material design strategies, photophysical properties, proposed mechanisms, and applications are systematically summarized. Finally, recent research on and challenges related to organic polymer photocatalysts are discussed. This minireview will help readers to more easily understand the recent advances in and future direction of this field. [ABSTRACT FROM AUTHOR]

Conjugated polymer dots (Pdots) based on a series of BDT-based polymers with varied biaxially extended side-chain conjugations were prepared and employed for photocatalytic hydrogen production under visible light irradiation from aqueous solutions. The BDT-based polymers consisted of a dithiophedifluorobenzo[ c ][1,2,5]thiadiazole (DFBT) moiety as the acceptor unit and a BDT unit with different biaxially extended side-chains, including a alkyl-monothienyl group (T), a linear alkyl-dithiophene (2T) group, a branched alkyl-terthiophene (3T) group, and a fused alkyl-benzotrithiophene (B3T) group. The as-prepared Pdots based on these four polymers (PBDT-T, PBDT-2T, PBDT-3T, and PBDT-B3T) showed varied photophysical and electrochemical properties along with distinctive photocatalytic activity and long-term stability. Among them, the PBDT-B3T Pdots were showed to deliver a high photocatalytic efficiency of 14.1 mmol g−1 h−1 and a superior photocatalytic stability over 375 h in the presence of Pt as cocatalyst and ascorbic acid as sacrificial electron donors. Our results revealed that varying the structures of the biaxially extended side-chains endows a great flexibility in the photocatalytic activity of the polymers and the biaxially-extended conjugated side-chains can be a promising design strategy for the conjugated polymer to enhance the photocatalytic activity and stability. [Display omitted] Introduction of biaxially extended side-chains with varying conformational isomers of thiophenes onto the BDT polymers is highly beneficial for harvesting broad absorption region resulting in high photocatalytic efficiency and robust stability. • Introduction of side-chain with varying thiophene geometry onto the polymers helps for harvesting broad absorption region. • The results show that varying the side-chain have a great effect on the photocatalytic activity and stability of the polymers. • PBDT-B3T Pdots were demonstrated to provide enhanced photocatalytic performance with prolonged stability to over 375h. • This study manifests that the introduction of fused side-chains is highly beneficial for improving photocatalytic HER and stability. [ABSTRACT FROM AUTHOR]

The organic semiconducting polymer dots (Pdot) or nanoparticles exhibited a promising efficiency as photocatalyst for hydrogen production. This study reported a new Pdot-based photocatalyst constructed in the form of Donor-Acceptor-Metal cocatalyst (D-A-M cat). These D-A-M cat Pdots systems consisting of fluorene (F) as the donor, thienyl-benzo-dithiophene-dione (TBDD) as the acceptor and [Ir (TPy) 2 (acac)] as the metal complex, and their structural, thermal, electrochemical and photophysical properties were systematically demonstrated for the first time. Introducing the cyclometalated iridium (III) complex comonomer into the polymer chain resulting in PFTBDD-IrTPy Pdots showed enhancement of the hydrogen evolution rates, which is over 20-times higher than those of pure polymer (PFTBDD Pdots) under otherwise identical conditions. In addition, the optical and electrical measurements indicated that the cyclometalated iridium (III) part have an important function for inhibiting the charge recombination of the PFTBDD-IrTPy Pdots during the photocatalytic reaction. The result strongly implies that inserted catalytic amount of Ir(III)-complex into the D-A polymers is beneficial for the enhancement of photocatalytic hydrogen evolution, which can inspire further optimization and greater molecular design strategies at a low-cost are highly desirable for the development of high-performance in photocatalysis. Image 1 • Donor and acceptor with cyclometallic Ir-based polymer dots (D-A-M cat Pdots) are developed for hydrogen evolution. • The systematic study of PFTBDD-IrTPy Pdot of their thermal and photophysical properties are discussed. • PFTBDD-IrTPy Pdot is a potential candidate for high HER activity as compared to PFTBDD Pdots. • Introduction of Ir(III)-complex into the PFTBDD polymers is beneficial for the enhancement of photocatalytic activity. [ABSTRACT FROM AUTHOR]

• Highly stretchable and self-healing materials based on metal–ligand coordination. • Choice of solvents can significantly affect the results of fabricated products. • SAXS/WAXS models constructed under different scenarios. • Robust skin-inspired pyramidal sensors can be performed over 100 cycles. Self-healing and stretchable materials have attracted considerable attention due their wide potential applications in developing human–machine interfaces. However, it remains a great challenge to achieve polymeric materials capable of both self-healing at room temperature and fast elastic recoverability after cuts or high stretching. We report herein a new material based on tolylene 2,4-diisocyanate elastomer (PTD) terminated with 4,4′-Bis(hydroxymethyl)-2,2′-bipyridine (bpy), having autonomously self-healing and ultra-fast stretching recovery properties, through incorporating trans -octahedral metal–ligand coordination of Zn2+ or Ni2+ ions with the bpy moieties; both Zn- and Ni-bpyPTD show combined properties of water-resistant, anti-bacteria, low toxicity and high transparency, and of respective emphases in self-healing and mechanical strength. The underlying mechanism is associated with the trans -octahedral metal–ligand coordination and their organized nanostructures as effective crosslinking sites in the bpyPTD matrix of rich hydrogen bonding, as revealed by X-ray absorption and in-situ small- and wide-angle X-ray scattering. Particularly, when fabricated into a pressure sensor, Ni-bpyPTD exhibits synchronized and durable mechanical and electrical responses under a repetitive cycling tensile testing up to 300% strain within 60 s, over 100 cycles, and would serve as a promising material for skin-inspired tactile sensing. [ABSTRACT FROM AUTHOR]

[Display omitted] • A library of cyclopentadithiphene-based polymer photocatalysts have been synthesized for photocatalytic hydrogen evolution. • PCPDTBSO exhibited hydrogen evolution rates up to 24.6 mmol h–1 g–1 with AQY of 8.7 % at 500 nm irradiation. • A strategy to select a suitable sacrificial donor according to the band gap of the polymer photocatalysts. • Ascorbic acid and triethylamine are suitable for polymer photocatalysts with wide and narrow band gap, respectively. A library of donor-acceptor system consisting of cyclopentadithiophene-based polymer photocatalysts have been designed and synthesized. Among all photocatalysts, the active PCPDTBSO achieved hydrogen evolution rates of 24.6 mmol h–1 g–1 with apparent quantum yields of 8.7 % at 500 nm. More importantly, combined the results of photocatalytic efficiency, apparent quantum yield, the time-resolved fluorescence decay spectra, the steady-state photoluminescence spectra, and the transient absorption spectroscopy, and the oxidation potentials of sacrificial donors and protons reduction potentials in different pH values, we confirmed the concept that ascorbic acid is a suitable sacrificial donor for narrow bandgap polymers and triethylamine is a suitable sacrificial donor for wide bandgap polymers owing to the existence of the optimal thermodynamic driving force. We believed this study would be advantageous for the selection of photocatalysts and sacrificial donors for hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • TPT-CMPs have a high photocatalytic efficiency, but low photocatalytic stability. • Sulfur doping enhanced photocatalytic stability for TPT-CMPs. • The synthesized materials in this work have high interest AQY values. • This work gives a new idea to boost stability without using noble metals. Conjugated microporous polymers (CMPs) have emerged in recent years as prospective materials for photocatalytic hydrogen production. The most common synthesis method for triazine is ionothermal synthesis at high temperatures (>350 °C), which also requires a large amount of ZnCl 2 , in which CF 3 SO 3 H-catalyzed method was invented to synthesize triphenyl triazine at room temperature. Herein, we reported the synthesis and characterization of two triazine-based conjugated micropores polymers photocatalysts at low temperature via polymerization of triphenyl triazine (TPT) with TPT and pyrene (Py). The TPT-based CMPs show excellent photocatalytic performance and a hydrogen evolution rate of 108.1 and 116.5 µmol h−1 under visible light for Py-TPT-CMP and TPT-TPT-CMP, respectively, but with low photocatalytic stability. In general, organic polymers add a small amount of platinum to efficiently produce H 2 with high photocatalyst stability. To provide a new opportunity to overcome the low stability, a sulfur doping method using readily available sulfur (S8) has been proposed which was used here for the first time to achieve a highly photocatalyst stability development without the use of noble metals. The as-synthesized polymers after sulfur doped exhibit an enhanced photocatalytic stability which can keep the hydrogen production for a long period of time without loss in the photocatalytic efficiency. Furthermore, our triazine-based CMP materials have interest apparent quantum yield (AQY) values particularly for Py-TPT-CMP and TPT-TPT-CMP which exhibit AQY of 41.9 and 32.38%, respectively at 420 nm, these values are compatible with the highest AQY of organic photocatalysts up to date. This study makes a significant contribution forward for photocatalysis with polymers because it provides excellent HERs and AQYs for the sulfur-doped triazine-based CMPs with high thermal, chemical, and photo stabilities. As well as, this work could give researchers in the field a different opinion on the effect of sulfur-doping. [ABSTRACT FROM AUTHOR]

A series of new triptycene-based discontinuously conjugated covalent organic polymer photocatalysts is developed for visible-light-driven hydrogen evolution. Although triptycene interrupts the continuous conjugation length, the absorption of the short-conjugated segment is sufficient to harvest the visible light irradiation. DPBT-TP with rod-like shape affords a high hydrogen evolution rate of 17,806 μmol g−1 h−1. • A series of Triptycene-Based Discontinuously-Conjugated Polymer is constructed for photocatalytic H 2 evolution. • Based on our design, the absorption of the short-conjugated is sufficient to harvest the visible light to produce hydrogen. • DPBT-TP COP affords an excellent HER of 17,806 μmol g−1 h−1, which is a significant enhancement in comparison to others. • Interestingly, by tuning the short-conjugated linker, the COP photocatalysts exhibited various shape. Effective photocatalytic systems that are capable of converting solar energy into chemical fuels have recently attracted significant attention. Covalent organic polymers (COPs) have been explored as promising photocatalysts for visible-light-driven hydrogen evolution from water. Herein, a series of triptycene (TP)-based discontinuously conjugated COP photocatalysts are described for the first-time using TP with monothiophene (MT), trithiophene (TT), dithiophene benzothiadiazole (DTBT), and diphenyl benzothiadiazole (DPBT), denoted as MT-TP, TT-TP, DTBT-TP, and DPBT-TP, respectively. Difference photophysical, morphological, and photocatalytic properties can be tuned by introducing different types of linkers of the TP-based COPs. DPBT-TP shows a significant enhancement of the hydrogen evolution rate (HER) in comparison to those using other polymer photocatalysts at identical conditions. The transmission electron microscopy/scanning electron microscopy data show that the tube-like polymer photocatalysts afford higher HERs than those observed with the particle-like polymer photocatalysts. This report describes the first demonstration that the polymer photocatalysts constructed by the disconuiously conjugated system (conjugation length: less than 5 aromatic rings) is sufficient for an efficient visible-light-driven hydrogen evolution. It provides an alternative material design strategy for polymer photocatalysts to achieve efficient visible light hydrogen evolution. [ABSTRACT FROM AUTHOR]

• The first systematically study of the effect of cycloplatinated Pdots with various acceptor co-monomers. • The use of TBTA co-monomer show no obvious color change after 9 h photocatalytic reaction, while TBDD one is totally changed after 6 h. • MTT assay for photocatalysts prove the low toxicity of our cycloplatinated Pdots. • TBTA-based Pdots achieve higher HER than TBDD-based Pdots, even though TBDD one has more red-shifted absorption spectra. • Cylcoplatinated Pdots can be reactivated for hydrogen generation by the recycling process. By mimicking nature photosynthesis, a library of cycloplatinated polymer dots (Pdots) and pristine Pdots are presented and investigated the importance of selecting acceptor comonomers. A clear design strategy for the selection of acceptor comonomers of Pdots to achieve environmental-friendly, high efficiency, and long stability of photocatalytic reaction can be understood. The active PFTBTA-PtPy Pdots provide the excellent hydrogen evolution rates up to 7.34 ± 0.82 mmol h–1 g–1 under a methanol-free solution and visible-light-driven system. MTT assay experiments confirm the use of the cycloplatinated Pdots as photocatalysts can minimize the toxicity, relative to the conventional approach that directly adding Pt into a solution system. Furthermore, the Pdots can be reactivated for hydrogen generation by the recycling process. The result proves that the use of cycloplatinated Pdots can not only enhance the HER efficiency and stability but also reduce the toxicity. [ABSTRACT FROM AUTHOR]