In situ reduced WO_3-xnanopowders from bulk tungsten:one-step electrosynthesis and electrochromic energy storage application AITranslate

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Chinese Library Classification Number:TB383[一般工业技术—材料科学与工程]

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Tungsten(W)is considered a critical and strategic material,the recycling of which has proved extremely important due to the substantial amount of W-rich waste and rising demand for W products.This study provides a sound technological approach for efficient utilization of bulk W,achieving a high W destruction rate(rw)of 0.3 g·cm^-2·h^-1via electrochemical oxidation/in situ reduction of W electrodes in oxalic acid under alternating current(AC)with varying symmetries to synthesize WO_3-xnanopowders(NPs).Amorphous-crystalline dual-phase reduced WO_3-xNPs featuring dense and porous nanoarchitectures were synthesized using asymmetrical and symmetrical AC,respectively.The nano scale interconnecting flaky WO_3-xstructure arises from the synergy of high anodic voltage etching and the release of H₂microbubbles,boosting the exfoliation of WO₃flakes.The optimized WO_3-xNP exhibits superior electrochemical and electrochromic properties,attributed to the increased surface capacitance alongside an extra contribution from intercalation pseudocapacitance.The number of WO_3-xlayers deposited by the spin coating technique and the annealing temperature have a significant impact on the electrochemical and electrochromic characteristics of the WO₃film.An increase in the transferred charge density(Q),coloring/bleaching time(t_c/t_b)values,and areal capacitance was observed,alongside a decrease in optical modulation(ΔT)and coloration efficiency(CE)with an increasing number of WO₃layers.WO₃produced at a lower temperature outperforms WO₃treated at 400-500℃,particularly in fast switching,enhanced efficiency,and reversibility.TheΔT of 68.7%,CE of 47.9 cm²·C^-1,areal capacitance of 53.5 mF·cm^-2,and reversibility close to 100%were achieved in H₂SO₄for the optimized WO_3-xfilm.The research aligns with the ongoing development strategy of the circular economy and validates the promising features of the efficient recycling of W-containing spent resources through an environmentally sustainable electrochemical approach.