To maximize the utilization of red mud in geopolymers, a red mud–metakaolin (RM-MK) geopolymer and red mud–fly ash (RM-FA) geopolymer were prepared, respectively. The effects of red mud content on the compressive strength and microstructure of the geopolymers were investigated under three different curing conditions. The results showed that the strength of the geopolymer decreased linearly with an increase in the red mud content, whether curing at room temperature or 80 °C. Surprisingly, curing in an autoclave, the appropriate amount of red mud had a favorable impact on the mechanical properties of the geopolymers. When the amount of red mud was 50%, the strength of the RM-MK geopolymer reached its highest compressive strength, 36.3 MPa, and the strength of the RM-FA geopolymer reached its highest at 31.7 MPa. Compared with curing at low temperature, curing the red mud-based geopolymers under a higher temperature and higher pressure can maximize the use of red mud. XRD analysis indicated that zeolite minerals formed. The SEM results showed that the geopolymers cured in an autoclave had a dense structure.

With the ever-increasing demand for energy, research on energy storage materials is imperative. Thereinto, dielectric materials are regarded as one of the potential candidates for application in advanced pulsed capacitors by reason of their ultrahigh energy-storage density, low energy loss, and good thermal stability. Among the numerous dielectric materials for energy storage, sodium bismuth titanate (Bi_0.5Na_0.5TiO₃, BNT) with high saturation polarization, as one of the successful alternatives to lead-based materials, has been extensively studied. However, degraded dielectric and ferroelectric properties as a consequence of chemical alterations usually produced by inhomogeneity in microstructure and composition due to the ion volatilization during preparing, thus affecting performance of devices. Hence, this review served to encompass the current state and progress on the optimization of energy storage performance in lead-free BNT-based materials over the past few years, including ceramics, multilayer ceramics, thin films, and thick films, involved in solid solution modification, metal/metallic oxide doping, process optimization and other related aspects to optimize energy storage performance. Furthermore, some prospective approach in the improvement of energy storage performance for BNT-based materials were also provided in this work according to the existing theoretical and experimental results, to impel their practical application.

Water pollution caused by dye wastewater is a potential threat to human health. Using photocatalysis technology to deal with dye wastewater has the advantages of strong purification and no secondary pollution, so it is greatly significant to look for new visible-light photocatalysts with high photocatalytic ability for dye wastewater degradation. Semiconductor photocatalyst silver phosphate (Ag₃PO₄) has high quantum efficiency and photocatalytic degradation activity. However, Ag₃PO₄ is prone to photoelectron corrosion and becomes unstable during photocatalysis, which severely limits its application in this field. In this study, a tubelike g-C₃N₄/Ag₃PO₄ heterojunction was constructed by the chemical precipitation method. An Ag₃PO₄ nanoparticle was loaded onto the surface of the tubelike g-C₃N_4, forming close contact. The photocatalytic activity of the photocatalyst was evaluated by the degradation of RhB under visible-light irradiation. The tubelike g-C₃N₄/Ag₃PO₄-5% heterojunction exhibited optimal photocatalytic performance. In an optimal process, the degradation rate of the RhB is 90% under visible-light irradiation for 40 min. The recycling experiment showed that there was no apparent decrease in the activity of tubelike g-C₃N₄/Ag₃PO₄-5% heterojunction after five consecutive runs. A possible Z-type mechanism is proposed to explain the high activity and stability of the heterojunction.