Humidity-dependent piezopotential properties of zinc oxide nanowires: Insights from atomic-scale modelling

Mechanisms underlying the shape effect on nano-piezoelectricity

“…We, therefore, form comparison with the previous simulations and theoretical models in predicting the size and shape effects on nano-piezoelectricity. It is shown that the shape effect on ZnO nanostructures and the importance of thickness t for ZnO h-NTs obtained in this work agrees qualitatively with MDSs [19,20] and the most recent theoretical model [32] for GaN nanostructues. The trend of to size change is also found to be consistent with the first-principles calculation for ultrathin ZnO and GaN NWs [14,28,29], e.g., the diameter from 0.6nm to 2.4nm [14].…”

“…As a result, a direct comparison cannot be achieved between the shape or size-dependence of obtained in the present simulations and the available experimental data. In the meantime, first-principles calculations [12,14,18,[26][27][28] (for ultra-thin nanostructures), molecular dynamics simulations (MDSs) [19,20,30,31] and a continuum model [32] have been efficiently used as an alternative way to investigate the size effect or shape effect on piezoelectricity of small pristine nanostructures that cannot be easily synthesized experimentally. We, therefore, form comparison with the previous simulations and theoretical models in predicting the size and shape effects on nano-piezoelectricity.…”

“…The development of piezoelectric nanostructures (PNs), in the recent decade, has led to practical ambient energy harvesters critical for self-powered nano-electronics [1,2] and provided an avenue towards prospective innovations in sensing [3], actuation [4], piezotronics [5,6] and biomechanical energy extractors [7]. A great deal of the effort has been devoted towards predicting the mechanical [8][9][10][11] and especially, piezoelectric behaviors and properties [12][13][14][15][16][17][18][19][20] of one-dimensional PNs. e.g.…”

Mechanistic pathway of water adsorption to impact on the nonlinear elasticity of single-crystalline ZnO NWs

“…Especially, the energetically favourable half-dissociative equilibrium adsorption structure is successfully obtained at 300K for {011 ̅ 0} surfaces 30,49 , which is key reason for its application in the studies of the wetting mechanics on ZnO surfaces and the humidity influence on the caxis ZnO NW piezo-potential generation. 34,51 Most importantly, the structural relaxation -a vital part of the surface effect -on the pristine free surface as well as its change due to water adsorption is reproduced.…”

“…A down shift of the conduction band edges is also observed but found to have a trivial influence on the overall piezopotential. 34 Hence, with substantial demonstrable NW property alternations observed it is inherently valuable to further quantify the adsorption influence on the elastic properties of ZnO NWs and attempt to draw a mechanistic understanding.…”