外加偏壓光-電轉(zhuǎn)化效率(Applied Bias Photon-to-current Efficiency,ABPE)是在一定偏壓條件下,,輸入的太陽能與轉(zhuǎn)化為氫能的比例[1],。
區(qū)別于太陽能制氫能轉(zhuǎn)換效率(STH),ABPE是扣除電能貢獻的能量轉(zhuǎn)化效率,。
在研究單一光電極的PEC分解水性能時,,通常會使用外加電源施加較小偏壓。此時,,為評估光電極的光電轉(zhuǎn)化效率,,可由公式(1)簡化為計算單一光陽極電解池的ABPE公式:
通常情況下,在法拉第效率為100%的條件下,,通過j-V曲線將jP,、Va和相應(yīng)的Pin帶入公式(2)即可計算獲得ABPE。
對于單一光陰極電解池則采用公式(3)計算ABPE:
由公式(2)可以發(fā)現(xiàn),,到當Va取1.23 V時,,ABPE的值幾乎為零,當Va的取值>1.23 V(vs. RHE)時,,ABPE的值為負數(shù),,因此在測光陽極的光電流密度時盡量選擇<1.23 V(vs. RHE)的外加偏壓值,并應(yīng)以提高外加偏壓<1.23 V(vs. RHE)范圍內(nèi)的光電流密度為研究目標,。
注意事項
計算時需要注意的以下兩點:
①以上計算公式僅適用于單室光電反應(yīng)池,,即電極需要在同一電解液中,避免產(chǎn)生化學電勢,。
②電解質(zhì)溶液中應(yīng)不含電子或空穴犧牲試劑,,雖然犧牲試劑可以很好的解決載流子在界面處的傳輸限制,但這將導致溶液中的反應(yīng)復雜化,,非原本的光電反應(yīng),。
圖1 ABPE 曲線[2-5]
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