Energy harvesting using two-dimensional magnesiochromite (MgCr2O4)

Two-dimensional (2D) materials with high surface activity can be utilized for harvesting energy from small mechanical sources using flexoelectricity. In the present work, we have synthesized an atomically thin 2D spinel MgCr2O4 by a liquid-phase exfoliation process, and characterization shows the preferential exfoliation along the (111) plane with low formation energy. The fabricated flexoelectric device produces an electrical response up to ∼3 V (peak-to-peak voltage) upon pressing and releasing the cell with ∼0.98 N force. Furthermore, the energy harvesting properties of 2D MgCr2O4 are explored by combining bending with other sources of external energy, with applied varying magnetic flux (Vmax = ∼2.6 V) and temperature with 0.9 N force (Vmax = ∼18 V). Our calculations determine that 2D MgCr2O4 has a flexoelectric coefficient of approximately μXZXZ = 0.005 nC/m. Overall, the results indicate that 2D MgCr2O4 is a very promising material for the next generation of self-powered wearable electronics and energy harvesting. The figure shows 2D magnesiochromite coated on cellulose substrate that works as a flexoelectric energy harvesting device. A simple vibration or mechanical force can generate enormous power output. The device is sensitive towards heat, vibration, deflection and magnetic flux and generates instant energy when interacts with any of these. [Display omitted] •Nanosheet produced by liquid-phase exfoliation of MgCr2O4 (1 1 1) provided scope for tuning Cr–Cr bonding to enhance energy harvesting properties.•Dipole change from point to point inside material due to the atomic strain led to maximum voltage output, resulted in flexoelectric effect.•Two-dimensional MgCr2O4 has flexoelectric coefficient (μXZXZ) upto ∼0.005 nC/m.