Synthesis of borophene on quartz towards hydroelectric generators

Abstract

Borophene has been identified as a rising star in the development of energy conversion and storage devices, sensors and detectors due to its distinctive physical and chemical properties. However, the reported borophenes based on molecular beam epitaxy, chemical vapor deposition and liquid-phase exfoliation suffer due to the easily oxidized structure, complicated transfer process or uncontrollable quality. It is very important for its potential application to develop a method for growing structurally stable borophene directly on an insulating substrate without a transfer process. Here, we report the growth of borophene on insulating quartz via chemical vapor deposition with hydrogen as a carrier gas and NaBH₄ as a boron source. The borophene film grown on quartz is called “borophene glass”. The as-synthesized borophene coincides well with the α′-2H-borophene predicted by first-principles calculations. To demonstrate the potential application of borophene glass, a novel borophene hydroelectric generator was fabricated to harvest the energy in water and transform it into useful electricity. The induced voltage and power density of the borophene hydroelectric generator are, respectively, up to 4.3 V and 501.7 μW m⁻², which are superior to those of carbon-based hydroelectric generators. The electrokinetic theory can be used to interpret the induced electricity from the borophene hydroelectric generator. This work paves the way for the physicochemical exploration of large-area borophene films on insulating substrates for its disruptive applications in energy conversion and storage devices as well as sensors.