Surface oxidation: an effective way to induce piezoelectricity in 2D black phosphorus

In this letter, first-principles methods are employed to investigate the elastic stiffness and piezoelectric tensors of surface-oxidized black phosphorene. Our results show that the piezoelectric coefficients d(11) and d(12) for surface-oxidized black phosphorene are 88.54 pm V-1 and -1.94 pm V-1, respectively, which are comparable to those of group-IV monochalcogenides and more remarkable than those of the experimentally viable h-BN and MoS2. These results indicate that surface-oxidization is an effective way to make black phosphorene into an excellent piezoelectric material for potential applications in sensors, actuators, electric field generators and any other applications requiring electrical and mechanical energy conversion. We expect further experimental exploration on this interesting result to confirm our predictions.