Electricity generated from ambient heat across a silicon surface

Abstract

These authors contributed equally to this work.We report that electricity can be generated from limitless thermal motion of ions by two dimensional (2D) surface of silicon wafer at room temperature. A typical silicon device, on which asymmetric electrodes with Au and Ag thin films were fabricated, harvested by 2D semiconductor surfaces or low dimensional materials and would contribute significantly to the research of renewable energy. However, this finding does not agree with the second law of thermal dynamatics, and a lot of future work will be need to study the mechanism behind this phenomenon.Self-powered technologies, such as harvesting energy by piezoelectric effect based on ZnO nanowires and from flowing 20 liquids or gases across graphene and carbon nanotubes, have attracted intensive interests.1-7 However, the low output power, as well as the poor reliability are limiting their practical application. Ambient heat, which is a limitless energy source, presents universally as a form of kinetic energy of molecular, atom, particle, 25 ion and electron in gas, liquid and solid states. Recently, we reported electricity generated from the thermal motion of ions in aqueous electrolyte solutions at room temperature by atomic layer 2D materials, such as graphene and reduced graphene oxide. 8,9 Semiconductor surface, which can be reagarded as 2D material, 30 is unstable and tends to be autocompensated because a large number of dangling bonds on the surface results in the appearance of delocalized electronic surface states and unstable Fermi level. [10][11][12][13][14][15] The cations on solid-liquid interface, which are governed by electrochemical double layer, are under thermal motion with a 35 velocity of hundreds of meters per second at room temperature. [16][17][18][19] This unlimited thermal motion can offer the opportunity for momentum transformation between the electrons and the ions and thun excited the unstable electrons to be free electrons.Thus, it is possible to harvest energy in terms of limitless thermal motion of 40 ions by semiconductor surface.Here, we investigated the silicon (Si) devices with asymmetric electrodes configuration to capture such ionic thermal energy and convert it into electricity. Two kinds of metal electrodes with different work functions (Au and Ag) are adopted to achieve 45 Ohmic and Schottky contacts in series for the rectifying function. A possible dynamic drag mechanism is proposed to interpret the energy transformation process. This finding shows potential of harvesting energy from ionic thermal motion at room temperature and will benefit the self-powered technology. , was cleaned in 5% HF for 2 mins to etch the oxidation layer away, then Au and Ag electrodes were deposited on either side of the Si surface by thermal evaporation. 65All the electrodes were sealed from exposing to the electrolyte solution. The exposed area was around 0.3 × 0.8 cm 2 between the electrodes. Fabrication processes of the device are shown in fig. S1. Then, the device was put into aqueou...

Synthesis of borophene on quartz towards hydroelectric generators

“…The thickness of the electrical double layer, so-called Debye length between the surface and the boundary of the diffuse layer, 45 can be expressed by:where κ −1 , k B , T , ε r , ε 0 , N A κ−1kBTεrε0NA , e , and I are the Debye length, Boltzmann constant, the absolute temperature in Kelvin, the dielectric constant of the solution, the permittivity of free space, the Avogadro number, the elementary charge and the ionic strength of the electrolyte, respectively.…”