High-performance x-ray source based on graphene oxide-coated Cu₂S nanowires grown on copper film

Abstract

Full static x-ray computed tomography (CT) technology has enabled higher precision and resolution imaging and has been applied in many applications such as diagnostic medical imaging, industrial inspection and security screening. In this technique, the x-ray source section is mainly composed of a thermionic cathode and electron beam scanning system. However, they have several shortcomings such as limited scanning angle, long response time and large volume. Distributed and programmable cold cathode (i.e. carbon nanotubes, ZnO nanowires (NWs)) field-emission x-ray sources are expected to solve these problems. However, there have been several long-standing challenges to the application of such cold field emitters for x-ray sources, such as the short lifetime and rigorous fabrication process, which have fundamentally prevented their widespread use. Here, we propose and demonstrate a cold field-emission x-ray source based on a graphene oxide (GO)-coated cuprous sulfide nanowire (Cu2S NW/GO) cathode. The proposed Cu2S NW/GO x-ray source provides stable emission (>18 h at a direct voltage of 2600 V) and has a low threshold (4.5 MV m−1 for obtaining a current density of 1 μA cm−2), benefiting from the demonstrated key features such as in situ epitaxy growth of Cu2S NWs on Cu, nanometer-scale sharp protrusions within GO and charge transfer between the Cu2S NWs and GO layer. Our research provides a simple and robust method to obtain a high-performance cold field emitter, leading to great potential for the next generation of x-ray source and CT.

Metal–Organic Frameworks‐Derived Self‐Supported Carbon‐Based Composites for Electrocatalytic Water Splitting

“…CoNi alloy nanoparticles and CNTs deposited N‐doped carbon nanosheet arrays on carbon cloth (CoNi alloy/NCNSAs/CC) were prepared by calcining the polymetallic organic framework precursors at 800 °C Ar/H 2 annealing. In the pyrolysis process, Co 2+ and Ni 2+ ions as the metallic nodes were simultaneously reduced to form CoNi alloy nanoparticles, and evenly embedded in N‐doped carbon nanosheet arrays and the formed alloy nanoparticles were subsequently used as the catalysts for the production of CNTs (Figure 3d) [145] …”

“…CoNi alloy/NCNSAs/CC showed a Tafel slope of 55 mV dec −1 , which was lowest in all samples, suggesting the favorable OER kinetics. The long‐term stability of CoNi alloy/NCNSAs/CC was tested and the data indicated that no change in polarization plots was observed after 3000 potential sweep cycles, declaring CoNi alloy/NCNSAs/CC possessed excellent catalytic stability in alkaline medium [145] …”

Fully Vacuum-Sealed Diode-Structure Addressable ZnO Nanowire Cold Cathode Flat-Panel X-ray Source: Fabrication and Imaging Application

“…Due to their excellent field emission characteristics [4][5][6], one-dimensional (1D) nanomaterials such as carbon nanotubes (CNTs) and nanowires were explored as the cold cathode for X-ray source [7][8][9]. H. Sugie et al prepared the first CNT cold cathode X-ray tube and realized X-ray transmission imaging [10].…”