Jiang Zhiqi, Xiao Zhaohui, Tao Zui, Zhang Xu, Lin Shiwei
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University Haikou 570228 Hainan China
School of Materials Science and Engineering, Hainan University Haikou 570228 Hainan China.
RSC Adv. 2021 Aug 3;11(43):26534-26545. doi: 10.1039/d1ra04561j. eCollection 2021 Aug 2.
Efficient charge separation, in particular bulk charge separation (BCS), is one of the most critical factors in determining the performance of photoelectrochemical (PEC) water-splitting. The BCS enhancement of CdS/BaTiO (CdS/BTO) nanowires (NWs) in photoelectrocatalysis has rarely been reported. This paper describes a remarkable PEC properties promotion of the CdS/BTO NWs, which is confirmed to be a result of the enhanced BCS efficiency induced by the ferroelectric polarization. The vertical arrays of BTO NWs endow fast transfer of carriers. Meanwhile, CdS is decorated uniformly on the surface of BTO NWs, which ensures a wide range of light absorption. After two negative polarizations, the CdS/BTO NWs have successfully obtained a remarkable photocurrent density, achieving 459.53 μA cm at 1.2 V, which is 2.86 times that of the unpolarized sample. However, after two positive polarizations, the photocurrent density dramatically decreases to 40.18 μA cm at 1.2 V, which is merely 0.25 times the original value. More importantly, the photocurrent density reaches up to a prominent value of -71.09 mA cm at -0.8 V after two successive negative polarizations, which is a 40.87 mA cm enhancement with respect to the sample without poling. Significantly, at -0.8 V, the BCS efficiency of the CdS/BTO NWs is as high as 91.87% after two negative polarizations. The effects of ferroelectric polarization on the PEC performance of CdS/BTO NWs have been systematically studied. The results demonstrate that ferroelectric polarization, especially negative polarization, results in an internal electric field to tune band bending of CdS/BTO NWs, thus prominently enhancing the PEC performance.
高效的电荷分离，尤其是体电荷分离（BCS），是决定光电化学（PEC）水分解性能的最关键因素之一。CdS/BaTiO（CdS/BTO）纳米线（NWs）在光电催化中BCS增强的情况鲜有报道。本文描述了CdS/BTO NWs显著的PEC性能提升，这被证实是铁电极化诱导的BCS效率增强的结果。BTO NWs的垂直阵列赋予了载流子快速转移的能力。同时，CdS均匀地装饰在BTO NWs的表面，确保了广泛的光吸收。经过两次负极化后，CdS/BTO NWs成功获得了显著的光电流密度，在1.2 V时达到459.53 μA cm，是未极化样品的2.86倍。然而，经过两次正极化后，光电流密度在1.2 V时急剧降至40.18 μA cm，仅为原始值的0.25倍。更重要的是，经过两次连续负极化后，光电流密度在-0.8 V时达到高达-71.09 mA cm的显著值，相对于未极化样品增强了40.87 mA cm。值得注意的是，在-0.8 V时，经过两次负极化后CdS/BTO NWs的BCS效率高达91.87%。系统研究了铁电极化对CdS/BTO NWs的PEC性能的影响。结果表明，铁电极化，尤其是负极化，会产生一个内电场来调节CdS/BTO NWs的能带弯曲，从而显著提高PEC性能。
