Titanium dioxide (TiO2) nanotube arrays coupled with a narrow gap semiconductor—bismuth selenide (Bi2Se3)—exhibited remarkable enhancement in the photocathodic protection property for 304 stainless steel under visible light. Bi2Se3/TiO2 nanocomposites were successfully synthesized using a simple two-step method, including an electrochemical anodization method for preparing pure TiO2 and a chemical bath deposition method for synthesizing Bi2Se3 nanoflowers. The morphology and structure of the composite films were studied by scanning electron microscopy, energy dispersion spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. In addition, the influence of the Bi2Se3 content on the photoelectrochemical and photocathodic protection properties of the composite films was also studied. The photocurrent density of the Bi2Se3/TiO2 nanocomposites was significantly higher than that of pure TiO2 under visible light. The sensitizer Bi2Se3 enhanced the efficient separation of the photogenerated electron-hole pairs and the photocathodic protection properties of TiO2. Under visible light illumination, Bi2Se3/TiO2 nanocomposites synthesized by the chemical bath deposition method with Bi3+ (0.5 mmol/L) exhibited the optimal photogenerated cathodic protection performance for 304 stainless steel.

In this study, new organic-inorganic g-C₃N₄/CoAl-LDH nanocomposites were prepared and introduced to fabricate photocatalytic cement mortars by internal mixing, coating, and spraying. The photocatalytic depollution of both g-C₃N₄/CoAl-LDH and cement mortars was assessed by NO_x degradation reaction under UV-visible light irradiation. The study results suggested that the degradation efficiency of g-C₃N₄/CoAl-LDH nanocomposites improved with an increase in g-C₃N₄ content. The g-C₃N₄/CoAl-LDH_1.5 nanocomposite displayed the highest NO_x degradation capacity, which was about 1.23 and 3.21 times that of pure g-C₃N₄ and CoAl-LDH, respectively. The photocatalytic cement mortars which were all fabricated using different approaches could effectively degrade the target pollutants and exhibited significant compatibility between g-C₃N₄/CoAl-LDH and cementitious substrate. Among them, the coated mortars showed strong resistance to laboratory-simulated wearing and abrasion with a small decrease in degradation rate.

By using the hydrothermal method, carbon microspheres (CMS) were fabricated and used for electrode modification. The characteristics of CMS were investigated using various techniques. The biocompatible sensing platform was built by immobilizing hemoglobin (Hb) on the micrometer-sized CMS-modified electrode with a layer of chitosan membrane. On the cyclic voltammogram, a couple of quasi-reversible cathodic and anodic peaks appeared, showing that direct electrochemistry of Hb with the working electrode was achieved. The catalytic reduction peak currents of the bioelectrode to trichloroacetic acid was established in the linear range of 2.0~70.0 mmol·L⁻¹ accompanied by a detection limit of 0.30 mmol·L⁻¹ (3σ). The modified electrode displayed favorable sensitivity, good reproducibility and stability, which suggests that CMS is promising for fabricating third-generation bioelectrochemical sensors.

In this paper, a novel core@shell nanosphere (TiO₂@CoAl-LDH) based on layered double hydroxide (LDH) combined with a nano-TiO₂ semiconductor was synthesized and introduced to cementitious materials via spraying technology and a smearing method. The compatibility with a cementitious matrix and the effects of TiO₂@CoAl-LDH on cement hydration, surface microstructure, and the microscopic mechanical properties of mortar were investigated by AFM, microhardness testing, FESEM, and BET analysis. Meanwhile, the effects of TiO₂@CoAl-LDH introduction methods on the photocatalytic performance and durability of the photocatalyst were systematically evaluated by methylene blue (MB) removal ratio and wear testing. The results show that TiO₂@CoAl-LDH exhibits enhanced compatibility with cementitious matrices and a higher photocatalytic capacity than individual CoAl-LDH and nano-TiO₂. The photocatalytic mortar prepared via spraying technology (CM-C) displays a higher photocatalytic capacity than that prepared via the smearing method (CM-S). Among them, the mortar with two layers of photocatalytic coatings (CM-C2) has the highest MB removal ratio, which reached 95.1% within 120 min of UV-visible light irradiation. While on the other hand, the wear test revealed that the smeared mortar has a higher photocatalytic capacity and better photocatalyst durability than the sprayed mortar. This work is expected to contribute to the development of multifunctional sustainable building materials.