A PPY/TiO₂/PPY jacket nanotube array was fabricated by coating PPY layer on the external and internal surface of a tube wall-separated TiO₂ nanotube array. It shows coaxial triple-walled nanotube structure with two PPY nanotube layers sandwiching one TiO₂ nanotube layer. PPY/TiO₂/PPY reveals much higher current response than TiO₂. The theoretical calculation indicates PPY/TiO₂/PPY reveals higher density of states and lower band gap, accordingly presenting higher conductivity and electroactivity, which is consistent with the experimental result of a higher current response. The electroactivity is highly enhanced in H₂SO₄ rather than Na₂SO₄ electrolyte due to feasible pronation process of PPY in an acidic solution. PPY/TiO₂/PPY could conduct the redox reaction in H₂SO₄ electrolyte which involves the reversible protonation/deprotonation and HSO₄⁻ doping/dedoping process and accordingly contributes to Faradaic pseudocapacitance. The specific capacitance is highly enhanced from 1.7 mF cm⁻² of TiO₂ to 123.4 mF cm⁻² of PPY/TiO₂/PPY at 0.1 mA cm⁻² in H₂SO₄ electrolyte. The capacitance also declines from 123.4 to 31.7 mF cm⁻² when the current density increases from 0.1 to 1 mA cm⁻², presenting the rate capacitance retention of 26.7% due to the semiconductivity of TiO₂. A PPY/TiO₂/PPY jacket nanotube with high charge storage capacitance is regarded as a promising supercapacitor electrode material.

中文翻译：

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PPY / TiO2 / PPY护套纳米管阵列的制备及电荷存储电容

通过在管壁分离的TiO ₂纳米管阵列的内外表面上涂覆PPY层来制备PPY / TiO ₂ / PPY护套纳米管阵列。它显示了同轴的三层纳米管结构，其中两层PPY纳米管夹着一层TiO ₂纳米管。PPY / TiO ₂ / PPY显示出比TiO ₂高得多的电流响应。理论计算表明，PPY / TiO ₂ / PPY具有较高的态密度和较低的带隙，因此具有较高的电导率和电活性，这与较高电流响应的实验结果一致。H ₂ SO _4中的电活性大大提高而不是Na ₂ SO ₄电解质，这是因为在酸性溶液中可行的PPY内旋过程。PPY /的TiO ₂ / PPY可以进行H中的氧化还原反应₂ SO ₄电解质涉及可逆的质子化/去质子化和HSO ₄ ^-的掺杂/脱掺杂过程，并相应地有助于法拉第假电容。在H ₂ SO _4中，在0.1 mA cm ^-2时，比电容从1.7 mF cm ^-2的TiO _2高至123.4 mF cm ^-2的PPY / TiO ₂ / PPY。电解质。当电流密度从0.1 mA cm ^-2增加到1 mA cm ^-2时，电容也从123.4降低到31.7 mF cm ^-2，由于TiO _2的半导电性，电容保持率达26.7％。具有高电荷存储电容的PPY / TiO ₂ / PPY外套纳米管被认为是有前途的超级电容器电极材料。