Robust Composites Based on Silicone Rubber for Self-Powered Piezoelectric Nanogenerators

Obtaining robust power density through piezoelectric nanogenerators (PENGs) is very challenging. Challenges include achieving good mechanical stability, optimum stiffness, reasonable voltage generation, limited heat dissipation, and power density as needed. This work focused exactly on these areas, and hybrid filler emerged as a promising candidate among the composites studied. For example, hybrid fillers exhibited optimized properties suitable for self-powered engineering applications. The composites fabricated in this work were based on titanium oxide (TiO₂), molybdenum disulfide (MoS₂), and silicone rubber (SR) as a host matrix. The results showed that TiO₂ represents a good reinforcing filler, while MoS₂ exerts a lubricating effect, improving the composites' mechanical strength and elongation at break. For example, the compressive modulus at 8 per hundred parts of rubber (phr) was 2.39 MPa (TiO₂), 1.62 MPa (MoS₂), and 2.1 MPa (hybrid filler). Similarly, the hysteresis loss at 5 phr was 20.09 J/m (TiO₂), 21.56 J/m (MoS₂), and 20.48 J/m (hybrid filler). Moreover, the elongation at break at 8 phr was 150% (TiO₂), 194% (MoS₂), and 170% (hybrid filler). In the same way, the electro-mechanical properties obtained were also robust. For example, the voltage output was ~22 mV (TiO₂), ~35 mV (MoS₂), and ~46 mV (hybrid filler). Moreover, the PENGs developed in this work generated power. For example, the power density was ~0.55 pW/cm² (TiO₂), ~1.03 pW/cm² (MoS₂), and ~1.56 pW/cm² (hybrid filler). Finally, the piezoelectric coefficient of the PENGs was 40 pC/N (TiO₂), 112 pC/N (MoS₂), and 160 pC/N (hybrid filler). These materials have a promising role in energy harvesting through self-powered nanogenerators for portable electronic systems. Finally, the low-power PENGs developed provide cost-effective voltage and power management circuits. This allows these PENGs to contribute to sustainable and self-sufficient electronic systems like pacemaker implants.