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Diatom frustules (DFs) with delicate hierarchical pores and a large specific surface area are extracted from artificially cultured diatoms, showing their utilization potential as shape-stabilized phase change materials (ss-PCMs). Herein, we successfully prepared a fully biomass-based ss-PCM, superhydrophobic thermal energy storage (STES) coating by employing beeswax (BW) as phase change materials (PCMs) and DFs as supporting materials via a facile spraying method. DFs can adsorb as much as 65 wt % BW without leakage, accompanied with a high heat storage capacity of 112.57 J/g. The thermal stability test demonstrates that the DF/BW coating can undergo 500 heating–freezing cycles with the reduction of the phase change enthalpy being less than 5%. Simultaneously, the DF also endows BW with a higher thermal degradation temperature (from ∼200 to ∼250 °C). In addition, the DF/BW coating shows superhydrophobicity due to the incorporation of the low surface energy of BW and the micro/nanostructures of DFs. This superhydrophobic surface can quickly and repeatedly recover its excellent water repellency through a simple heat treatment (80 °C, 20 min) after being damaged by a water impact or strong acid and alkali corrosion. This self-healing ability can effectively overcome the poor durability of traditional superhydrophobic materials. Our research can expand the application of DFs in the field of ss-PCMs and guide the preparation of durable superhydrophobic surfaces with rapid self-healing performance.

Taking advantage of simple structure and control, stick-slip piezoelectric actuators have been widely employed to realize precision positioning in precision machinery and instrument. However, their output characteristics could be significantly affected by the contact status between the driving mechanism and the mover (or rotor). If the contact status changes in the motion process, strong nonlinearity will appear in the displacement-time curve, deteriorating the performances. To achieve a constant contact status, the gravity of the rotor was used in this paper, and accordingly, a novel stick-slip piezoelectric rotary actuator was developed. The structure design, motion principle, as well as output characteristics of the actuator were addressed and discussed in detail. Experimental results indicated that when the driving frequency was below 350 Hz, stable stepping motions with quite small backward motion could be achieved. By changing the driving frequency, voltage and radius, various stepping rotation angles and speeds were easily obtained. The output characteristics changing with the vertical load were further characterized. Furthermore, by simply changing the direction of the driving waveform, forward and reverse rotation motions showing good linearity with time were achieved in a very large motion range, corresponding to a millimeter scale linear displacement. Comparative experiments with a normal stick-slip actuator further confirmed the validity and advancement of the proposed strategy for keeping a constant contact status, which will be beneficial to the subsequent motion control and mass production.