Multiferroic nanomaterials have attracted great interest due to simultaneous two or more properties such as ferroelectricity, ferromagnetism, and ferroelasticity, which can promise a broad application in multifunctional, low-power consumption, environmentally friendly devices. Bismuth ferrite (BiFeO₃, BFO) exhibits both (anti)ferromagnetic and ferroelectric properties at room temperature. Thus, it has played an increasingly important role in multiferroic system. In this review, we systematically discussed the developments of BFO nanomaterials including morphology, structures, properties, and potential applications in multiferroic devices with novel functions. Even the opportunities and challenges were all analyzed and summarized. We hope this review can act as an updating and encourage more researchers to push on the development of BFO nanomaterials in the future.

The self-powered sensors are more and more important in current society. However, detecting both light and temperature signals simultaneously without energy waste and signal interference is still a challenge. Here, we report a ZnO/graphene nanocomposite foam-based self-powered sensor, which can realize the simultaneous detection of light and temperature by using the conjuncted photo-thermoelectric effect in ZnO–graphene nanocomposite foam sensor. The output current under light, heating and cooling of the device with the best ZnO/graphene ratio (8:1) for the foam can reach 1.75 µA, 1.02 µA and 0.70 µA, respectively, which are approximately three fold higher than them of devices with other ZnO/graphene ratios. The ZnO–graphene nanocomposite foam device also possesses excellent thermoelectric and photoelectric performances for conjuncted lighting and heating detection without mutual interference. The ZnO–graphene nanocomposite foam device exhibits a new designation on the road towards the fabrication of low cost and one-circuit-based multifunction sensors and systems.

Through a two-step solvothermal method, different molar ratios of BiPO₄ were grown in situ on the surface of oxygen-vacancy-rich BiOBr (Ov-BiOBr), successfully constructing a BiPO₄/Ov-BiOBr heterojunction composite material. By constructing a novel type I high-low junction between the semiconductor BiPO₄ and Ov-BiOBr, stronger oxidative holes or reductive electrons were retained, thereby improving the redox performance of the photocatalyst. The composite catalyst with a 10% molar content of BiPO₄ demonstrated the highest degradation rate of tetracycline (TC), degrading over 95% within 90 min, with a rate constant of 0.02534 min⁻¹, which is 2.3 times that of Ov-BiOBr and 22 times that of BiPO₄. The 10% BiPO₄/Ov-BiOBr sample displayed the best photocatalytic activity, producing 139 μmol·L⁻¹ H₂O₂ in 120 min, which is 3.6 times the efficiency of Ov-BiOBr and 19 times that of BiPO₄. This was due to the appropriate bandgap matching between BiPO₄ and Ov-BiOBr, the photo-generated electron transfer channel via Bi-bridge, and efficient charge separation. It was inferred that the free radical species ·OH and ·O₂⁻ played the dominant role in the photocatalytic process. Based on experimental and theoretical results, a possible photocatalytic mechanism was proposed.