高效能鈷鎳氧硒化物電觸媒應用於水分解與染料敏化太陽能電池

Abstract

便宜且製備簡易的鈷鎳氧硒化物薄膜可成功藉由電沉積法與硒化程序來合成。使用可彎曲的碳布做為基材，成功製造出以一維碳纖維為導電核心，附著性良好的鈷鎳氧硒化物的薄膜為催化外殼的核-殼結構。當前驅鹽中鈷(II)/鈷(II)+鎳(II)的莫爾比增加從0.00到0.17時，鈷鎳氧硒化物顆粒大小下降而使電極表面積提升，讓CC/Co-10表現出對三碘離子最佳的還原能力。使用CC/Co-10當作染料敏化太陽能電池的對電極時，可以達到優異的光電轉換效率10.71%，甚至高於傳統的白金CC/Pt (9.38%)。當持續增加前驅鹽中鈷(II)/鈷(II)+鎳(II)的莫爾比從0.17到0.67，可大幅度增加電極中[Se2−]/[O2−+Se2−]的莫爾比，進而優化CC/Co-40電極於產氫反應(HER)的電催化能力，達到平均過電位(ηavg-HER)為215 mV (vs. RHE)、10 mA cm-2下的過電位為223 mV (vs. RHE)、100 mA cm-2下的過電位為556 mV (vs. RHE)、塔佛斜率為148 mV decade-1。同時CC/Co-40電極對於產氧反應(OER)也擁有最佳的電催化能力，達到平均過電位(ηavg-OER)為362 mV (vs. RHE)、10 mA cm-2下的過電位為362 mV (vs. RHE)、100 mA cm-2下的過電位為592 mV (vs. RHE)、塔佛斜率為116 mV decade-1；優於常見的CC/RuO2電極(ηavg-OER為392 mV vs. RHE)。經由調整CC/CoxNiyOmSen的化學計量比例，多功能的電催化CoxNiyOmSen材料可以根據三碘離子的還原、產氫、產氧等反應，各別進行材料優化來達到最佳的電化學表現，顯示其應用於不同電化學系統的無限潛力。Low-cost and easily-fabricated CoxNiyOmSen films were successfully prepared by using an electrodeposition method, followed by a selenization process. When using a flexible carbon cloth as a substrate, a core-shell structure of CC/CoxNiyOmSen was established with decent adhesion by applying each onedimensional carbon fiber in CC as the conducting core and a CoxNiyOmSen film as the electro-catalytic shell. When increasing the molar ratio of [Co(II)]/[Co(II)+Ni(II)] mixing salt from 0.00 to 017, the shrunk particle size and the increased surface area on the CC/Co-10 electrode rendered an optimal electrocatalyticability toward I3− reduction. Therefore, a dye-sensitized solar cell coupled with CC/Co-10 as the counter electrode reached a superior solar-to-electricity conversion efficiency of 10.71%, even higher than the traditional CC/Pt (9.38%). When further increasing the [Co(II)]/[Co(II)+Ni(II)] molar ratio from 0.17to 0.67, the largely increased [Se2−]/[O2−+Se2−] atomic ratio and enhanced the electro-catalytic ability of CC/Co-40 electrode made a decent average overpotential (ηavg-HER) of 215 mV (vs. RHE), a specific overpotential at a current density of 10 mA cm−2 (η10-HER = 223 mV vs. RHE) or at a current density of100 mA cm−2 (η100-HER= 556 mV vs. RHE), and a cathodic Tafel slop (βc) of 148 mV decade−1 for hydrogen evolution reaction (HER). Meanwhile, the same CC/Co-40 electrode also reached an optimal average overpotential (ηavg-OER) of 362 mV (vs. RHE), a specific overpotential at a current density of 100 mA cm−2 (η100-OER= 592 mV vs. RHE), and an anodic Tafel slop (βa) of 116 mV decade−1 for oxygen evolution reaction (OER); it showed a better OER activity than the common CC/RuO2 (ηavg-OER of 392 mV vs. RHE). Via tuning the stoichiometric ratio of the CC/CoxNiyOmSen electrode, multiple functional electro-catalyst of CoxNiyOmSen was independently optimized to reach op electrochemical performance toward I3− reduction, HER, and OER, indicating its infinite potential to be applied in various electrochemical systems.