Conjugated microporous polymers (CMPs) have been investigated in the field of photocatalytic hydrogen production because of their extended π-conjugation, tunable chemical structure and excellent thermal stability. Herein, we construct three CMPs based on thiophenes and triazine, and prove the effect of cross-linker length on photocatalytic activity of CMPs. BTPT-CMP1 exhibits blue-shifted optical absorption compared to BTPT-CMP2 and BTPT-CMP3 with long cross-linkers, however, possesses higher photocurrent because of the large specific surface area and small interface charge transfer resistance of BTPT-CMP1. It was found that BTPT-CMP1 (5561.87 μmol g⁻¹ h⁻¹) with short cross-linkers exhibits better photocatalytic performance compared to BTPT-CMP2 (1840.86 μmol g⁻¹ h⁻¹) and BTPT-CMP3 (1600.48 μmol g⁻¹ h⁻¹). Also, BTPT-CMP1 possesses a higher hydrogen evolution rate than most reported 1,3,5-triazine based conjugated polymers. These results demonstrate that the cross-linker length has great influence on the photocatalytic properties of conjugated microporous polymers, which offers theoretical direction for designing high-performance CMPs.

In this study, a nitrogen-containing ligand supramolecule named PPYTZ was successfully synthesized using 2,6-pyridinedicarboxylic acid chloride and 3,5-diamino-1,2,4-triazole in order to carry out oxygen reduction reaction (ORR). Such a polymer provides abundant coordination sites for iron ions, and the PPYTZ–Fe/C composite catalyst was formed with the PPYTZ–Fe complex loading on the surface of Vulcan XC-72 carbon. The physical characteristics and ORR performance of the composite catalysts were characterized systematically via various relevant techniques, and their catalytic activity and reaction mechanism were evaluated and compared. The results showed that the catalytic activities and the reaction mechanism of ORR were highly dependent on the formation of an Fe–N unit. Accordingly, the PPYTZ–Fe/C catalyst containing Fe–N active sites exhibited high ORR catalytic activity (an onset potential of +0.86 V vs. RHE) in 0.1 M KOH. Such an Fe–N catalyst can accelerate the adsorption of O₂ and increase the limiting current density (from 2.49 mA cm⁻² to 4.98 mA cm⁻²), optimizing the ORR catalytic process from a two-electron process to a four-electron process (an n value of 3.8).

Three soluble conjugated polymers, named BEDPP, FLDPP, and CADPP, were prepared through the Suzuki polymerized reaction, and employed benzene (BE), fluorene (FL), and carbazole (CA) as the donor units, respectively. The electron-deficient molecule 2,5-bis-(2-octyldodecyl)-3,6-bis-(5-bromo-thiophene)-pyrrole[3-c]pyrrole-1,4-diketone(DPP) was introduced and used as the acceptor unit. The properties of these three copolymers were studied by a series of detailed characterization analysis, including X-ray photoelectron spectroscopy (XPS), colorimetry, electrochemical measurements, spectroelectrochemistry, kinetics, quantitative calculation, and thermogravimetric (TG) analysis, etc. The results revealed that BEDPP displayed a blue color in the neutral state and a light brown color in the oxidized state, FLDPP exhibited a cyan color in the neutral state and a gray color in the oxidized state, while CADPP displayed pure blue color in the neutral state and a light gray color in the oxidized state. All these polymers possess narrow optical band gaps lower than 1.80 eV and satisfactory thermal stability. The kinetic characterization showed that the optical contrasts (ΔT%) in the near-infrared region were superior to the visible region. The optical contrasts of BEDPP, FLDPP, and CADPP are 41.32%, 42.39%, and 45.95% in the near-infrared region, respectively, which made them a good application prospect in the near-infrared region. Amid the three polymers, CADPP has the highest coloration efficiency (around about 288 cm²·C⁻¹) and fast switching times (0.77 s in the coloring process and 0.52 s in the bleaching process) in the visible region, and the comprehensive performance of CADPP can be comparable to that of the reported D-A (Donor-Acceptor) type blue color polymers. In general, based on the good performances and the stable neutral blue color, the three polymers had profound theoretical significance for the development of electrochromic material and the completion of the RGB (Red, Green, Blue) color space.

Conjugated porous polymers (CPPs) incorporating donor–acceptor (D–A) structures are gaining significant interest for their potential in photocatalytic hydrogen evolution reaction (HER). The microstructure and electronic properties of the polymer frameworks are crucial for optimizing their photocatalytic efficiency. Here, we design two D–A type CPP photocatalysts using 4,8-di(thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (DBD) and triazine units to investigate the impact of different bridging units on HER activity. Compared with PhDBD–CPP using benzene as the bridging unit, ThDBD–CPP with a thiophene linking unit achieves an expansion of the HOMO orbital distribution and an enlarged molecular dipole moment, which is conducive to the efficient separation and migration of photogenerated carriers. Consequently, ThDBD–CPP with thiophene as the bridging unit exhibits a remarkable photocatalytic hydrogen evolution rate of 20.75 mmol h⁻¹ g⁻¹ under full arc light. After loading 1 wt% Pt cocatalyst, the HER activity is further improved to 30.36 mmol h⁻¹ g⁻¹. This study suggests that modulating bridging units provides a new viable approach to designing efficient polymer photocatalysts.

In this work, we modified the electronic structure of Pd by coating with MgO on the surface of Al₂O₃. Through in-depth research, we revealed the mechanism of MgO modification on the dispersion and stability of Pd active centers.