In this study, a method was developed to create oxygen vacancies in Cu₂O/TiO₂ heterojunctions. By varying the amounts of ethylenediaminetetraacetic acid (EDTA), sodium citrate, and copper acetate, Cu₂O/TiO₂ with different Cu ratios were synthesized. Tests on CO₂ photocatalytic reduction revealed that Cu₂O/TiO₂’s performance is influenced by Cu content. The ideal Cu mass fraction in Cu₂O/TiO₂, determined by inductively coupled plasma (ICP), is between 0.075% and 0.55%, with the highest CO yield being 10.22 μmol g⁻¹ h⁻¹, significantly surpassing pure TiO₂. High-resolution transmission electron microscopy and electron paramagnetic resonance studies showed optimal oxygen vacancy in the most effective heterojunction. Density functional theory (DFT) calculations indicated a 0.088 eV lower energy barrier for ∗CO₂ to ∗COOH conversion in Cu₂O/TiO₂ with oxygen vacancy compared to TiO₂, suggesting that oxygen vacancies enhance photocatalytic activity.

TiO₂ has low photocatalytic activity due to its easy recombination of photogenerated charges and low visible light utilization efficiency. This study utilized the keto-enol tautomerism principle of fructose in an alkaline environment to successfully obtain Cu₂O/TiO₂ (CT), Cu₂O/TiO₂/Cu (CTC), and TiO₂/Cu (TC) catalysts. As Cu(I) transformed into Cu(0), the bandgap narrowed, significantly enhancing visible light absorption. Photocatalytic tests showed that CT-0.15 exhibited the highest hydrogen production rate (279.53 μmol g⁻¹ h⁻¹), which was 25.18 times higher than that of TC-2. However, CTC-1 had the highest CO production rate (10.58 μmol g⁻¹ h⁻¹). Optoelectronic test revealed that CT-0.15 and CTC-1 had higher separation efficiency of photogenerated exciton. Density functional theory (DFT) calculations indicated that the change in the valence state of Cu influenced the reaction mechanism, with CT being favorable for the adsorption of H⁺ in HER and CTC promoting the adsorption of CO₂ in carbon dioxide reduction reaction (CO2RR).

At present, the scale of China’s power grid is becoming larger and larger, and the control of low‐frequency noise in substations (especially for transformers) is very important. The sound‐absorbing materials have become one of the important ways to control low‐frequency noise. The single polyurethane material cannot satisfy the requirements for reducing low‐frequency noise, so it is very necessary to study its composite with other materials. In the paper, the flexible polyurethane foam and Al₂O₃ nanoparticle composites were obtained by the impregnation method. The method was simple, safe, and easy to control. The morphology and sound absorption coefficient of the foam materials before and after filling were analyzed. Single‐hole acoustic cavity models of PU and Al₂O₃‐PU composite were established through the finite element. The absorption and dissipation process of sound pressure for single hole was studied to understand the energy dissipation process. Meanwhile, through studying acoustic energy storage and acoustic energy dissipation, the loss factor of a single hole was obtained, which can predict the change rule of the sound absorption coefficient for PU foam and Al₂O₃‐PU.