Metal-free porphyrin with good planarity is beneficial to π–π stack interactions, which promotes electron coupling and the separation and transfer of photogenerated carriers. It is necessary to develop metal-free porphyrin-based photocatalysts and exploit the photocatalytic mechanism. Herein, metal–free porphyrin (5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, TCPP) was self-assembled through an acid-based neutralization reaction and mixing dual-solvents under surfactants to form different aggregates. Morphology structures, optical and optoelectronic properties of the TCPP aggregates were characterized in detail. TCPP self-assemblies showed higher photocatalytic activities for the degradation of phenol under visible light than untreated TCPP powders, and the aggregates of nanorods formed through the acid-based neutralization reaction in the presence of hexadecyl trimethyl ammonium bromide (CTAB) possessed 2.6 times more activity than the nanofiber aggregates formed through mixing dual-solvents. It was proved that self-assembly methods are crucial for controlling the aggregation of porphyrins to form different aggregations, which have a profound impact on the photocatalytic activity.

Three-dimensional PANI/CdSNRs-SiO2 hydrogel (CdS NRs-PANI-SiO2) was synthesized by loading polyaniline (PANI) onto the semiconductor CdS nanorods (NRs) surface and loading the binary complex on SiO2 gel. The structure, optical properties, and electrochemical properties of the composite were studied in detail. The hydrogen production amount of CdS NRs-PANI (3%)-SiO2 (20%) increased in comparison with CdS NRs and reached 43.25 mmol/g in 3 h under visible light. The three-dimensional structure of SiO2 hydrogel increased the specific surface area of the catalyst, which was conducive to exposing more active sites of the catalyst. In addition, the conductive polymer PANI coated on CdS NRs played the role of conductive charge and effectively inhibited the photo-corrosion of CdS NRs. In addition, the recovery experiment showed that the recovery rate of the composite catalyst reached 90% and hydrogen production efficiency remained unchanged after five cycles, indicating that the composite catalyst had excellent stability.

Ursolic acid (UA) as a natural ursane-triterpenoid has rich pharmacological activities. We have found that it possesses aggregation properties and could self-assemble into organogels. Based on the aggregation property of ursolic acid in suitable solvents, its derivative appended with aromatic rings by amide groups was synthesized. The property of self-assembly into organogel was studied in this paper. The results revealed that this derivative could form supramolecular gel in halogenated benzene and also gelate chloroform in the presence of toluene or p-xylene. By Fourier-transform infrared spectra (FT-IR) and variable temperature proton nuclear magnetic resonance (¹H NMR), it was proved that intermolecular hydrogen bonding and π–π stacking interaction were the primary driving forces for the aggregation to form organogel.

Adsorption is a highly promising and widely used approach to remove Hg(II) ions from contaminated water. The key to this technology is exploring the effective adsorbent. The three-dimensional (3D) graphene as reduced graphene oxide hydrogel (rGH)-encapsulated silica gel (SG-PEI/rGH) was prepared by a moderate chemical reduction strategy using ascorbic acid. This composite structure was characterized by FTIR, XRD, and SEM analysis and used as adsorbents for Hg(II) ions. Its adsorption capacity toward Hg(II) ions was 266 mg/g and increased about 32% compared with the silica gel because of reduced graphene oxide hydrogel (rGH). Mechanism study showed that the high adsorption ability was due to the formation of an N–Hg complex with multi-amino groups on the surface of polyethyleneimine-modified silica gel (SG-PEI) and the rapid diffusion of adsorbed ions attributed to the rGH network structure. This composite SG-PEI/rGH would be a promising material for the removal of Hg(II) ions.