p-n异质结BiVO_(4)/g-C_(3)N_(4)光阳极的制备及其光电化学水解性能

p-n Heterostructured BiVO 4/g-C 3N 4 Photoanode:Construction and Its Photoelectrochemical Water Splitting Performance

钒酸铋(BVO)可用于光电化学(PEC)水解产氢,但受限于其缓慢的表面水氧化动力学,在电极表面修饰单一的析氧助催化剂达不到理想的性能。本工作在BVO电极表面修饰FeNiO_(x)助催化剂可以显著降低起始电压,增强光电化学性能。此外,沉积g-C_(3)N_(4)后修饰FeNiO_(x)助催化剂得到的光电极具有更优异的性能。厚度适合的g-C_(3)N_(4)纳米片与BVO构成Ⅱ型p-n异质结,有效抑制了光生电子空穴的复合,促进了电极的电荷分离。电化学测试结果表明,沉积了g-C_(3)N_(4)后,电极的电荷分离效率达到88.2%,比BVO/FeNiO_(x)(60.6%)提升了近1.5倍。经过g-C_(3)N_(4)和FeNiO_(x)协同修饰的BVO/g-C_(3)N_(4)/FeNiO_(x)电极,表面电荷注入效率达到了90.2%,同时,在1.23 V(vs.RHE)条件下光电流密度达到4.63 mA·cm^(–2),是纯BVO(1.86 mA·cm^(–2))的2.48倍。本工作为开发制备高性能光阳极提供了一种有效的策略。

Bismuth vanadate(BVO)can be used for photoelectrochemical(PEC)water splitting to hydrogen.However,suffering from its high charge-recombination and slow surface catalytic reaction,the PEC performance is far below the expectation,and the modification of the co-catalysts only on the electrode cannot overcome this disadvantage.Here,we report FeNiO_(x)cocatalyst decorated on the BVO photoanode,which can restrict the onset potential and improve the PEC performance.Moreover,a more effective dual modified-BVO photoanode is formed,with the loading of g-C_(3)N_(4)before decoration of FeNiO_(x)cocatalyst.The type-II p-n heterojunction composed by g-C_(3)N_(4)nanosheets and BVO,can inhibit recombination of photogenerated charge,and promote the separation of charge effectively at the electrode.Results show that the charge separation efficiency of the electrode reaches 88.2%after the insertion of g-C_(3)N_(4),which is nearly 1.5 times that of BVO/FeNiO_(x)(60.6%).Moreover,surface charge injection efficiency of the dual-modified BVO/g-C_(3)N_(4)/FeNiO_(x)electrode reaches 90.2%,while the current density reaches 4.63 mA·cm^(-2)at 1.23 V(vs.RHE).This work provides a facile approach to develope high performance photoanodes for PEC water splitting.