Abstract Charge-carrier dynamics during photoelectrochemical (PEC) water splitting over WO3 particulate photoanode deposited on titanium sheet (Ti/WO3) was studied using intensity-modulated photocurrent spectroscopy (IMPS). The WO3 particulate film calcined at 650 °C showed high PEC performance for water oxidation to evolve O2. In linear sweep voltammetry, the photocurrent density proportionally increased with incident light intensity (I0). This means that the incident photon-to-current conversion efficiency (IPCE) of Ti/WO3 was not dependent on I0 in voltammetry. In contrast, there was no proportional relation between I0 and the photocurrent density in chronoamperometry at a constant potential, indicating that the IPCE at steady state decreased with an increase of I0. To elucidate the effect of light intensity on the steady-state IPCE, we investigated the IMPS response of Ti/WO3 photoanodes by applying a simple branching model with respect to the photogenerated holes (h+). It was found that the recombination rate constant (krec) rather than the charge transfer rate constant (kct) significantly depends on I0 at the steady-state condition. The pseudo-first-order krec increased with an increase of I0, suggesting that recombination is increased by the accumulation of photogenerated carriers during continuous PEC water oxidation. This is the reason for the decrease in the steady-state IPCE of Ti/WO3 under high-intensity light irradiation. The effects of applied potentials on the kinetic parameters (kct and krec) were also evaluated for Ti/WO3 under different I0.

中文翻译：

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通过强度调制光电流光谱研究光强度对三氧化钨微粒光阳极稳态动力学的影响

摘要 使用强度调制光电流谱 (IMPS) 研究了沉积在钛片 (Ti/WO3) 上的 WO3 颗粒光阳极上光电化学 (PEC) 水分解过程中的电荷载流子动力学。在 650 °C 下煅烧的 WO3 颗粒膜显示出高 PEC 性能，可用于水氧化释放 O2。在线性扫描伏安法中，光电流密度随入射光强度 (I0) 成比例增加。这意味着 Ti/WO3 的入射光子到电流转换效率 (IPCE) 不依赖于伏安法中的 I0。相比之下，恒定电位下计时电流法中I0与光电流密度之间没有比例关系，表明稳态下的IPCE随着I0的增加而降低。为了阐明光强度对稳态 IPCE 的影响，我们通过对光生空穴 (h+) 应用简单的分支模型来研究 Ti/WO3 光阳极的 IMPS 响应。发现复合速率常数 (krec) 而不是电荷转移速率常数 (kct) 在稳态条件下显着取决于 I0。伪一级 krec 随着 I0 的增加而增加，表明在连续 PEC 水氧化过程中光生载流子的积累增加了复合。这就是在高强度光照射下 Ti/WO3 的稳态 IPCE 降低的原因。还评估了施加电位对不同 I0 下 Ti/WO3 的动力学参数（kct 和 krec）的影响。