LAUSR

Abstract Gallium oxynitride (GON) is emerging as an efficient component in the field of energy storage and conversion. However, the structure has not been well understood that is responsible for the improved properties. In this contribution, we devote to correlating the structure of GON with the physi-/electrochemical properties by virtue of experimental and theoretical studies. GON nanoparticles anchoring on the carbon cloth (CC) are prepared through a moisture-assisted ammonolysis method. The physi-/electrochemical properties of GON can be tuned by controlling the nitridation temperature (750–850 °C). The formation of GON, rather than Ga2O3/GaN mixture, is confirmed by XRD, diffuse reflection UV–Vis, and layer-by-layer thinning XPS techniques. The capacitive behavior of GON has been analyzed by combining electrochemical double layer capacitance with faradaic pseudocapacitance, which originates from intercalation/chemisorption of protons upon the GON matrix. After long-term cycling tests, pulverization and amorphization occur in GON. However, the symmetric supercapacitor assembled with GON@CC-800 manifests a nearly 100% capacitance retention relative to the initial capacitance (132 mF cm−2, 10 mA cm−2), after 20,000 charge/discharge cycles with varied current densities of 10–50 mA cm−2. At 1 mA cm−2, the device can deliver a specific energy of 21.1 μW h cm−2, with corresponding specific power of 0.5 mW cm−2. The impressive electrochemical performance of GON is related to the small particle size, defects, and elongated Ga–N bond length, due to the replacement of partial N with O.