The effects of the size, contact-angle, and coverage of gas bubbles on solar fuels devices were characterized at cm-scale, upward-facing planar and microwire-array Si photoelectrodes in stagnant electrolytes. Experimental measurements were supported by ray-tracing simulations of surface attached gas bubble films. A dilute, redox-active tracer allowed for the quantification of the mass-transport effects of bubble coverage during photoanodic O₂(g) evolution at upward-facing photoanodes in 1.0 M KOH(aq.). Measurements of the gas coverage at upward-facing p-Si photocathodes in 0.50 M H₂SO₄(aq.) allowed for the nucleation rate and contact angle of H₂(g) bubbles to be evaluated for systems having various surface free energies. Under simulated solar illumination, the rapid departure of small O₂(g) bubbles produced stable photocurrents at upward-facing oxygen-evolving Si photoanodes and yielded increased mass-transport velocities relative to a stagnant electrolyte, indicating that bubbles can provide a net benefit to the photoelectrochemical performance of an upward-facing photoanode in solar fuels devices.

中文翻译：

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H2和O2气泡在朝上的Si光电极上的光学和电化学效应

在停滞的电解质中，在厘米级，面朝上的平面和微线阵列Si光电极上，表征了尺寸，接触角和气泡在太阳能设备上的影响。表面附着气泡膜的射线追踪模拟为实验测量提供了支持。稀释的氧化还原活性示踪剂可量化在1.0 M KOH（aq。）中朝上的光阳极中光阳极O ₂（g）演变过程中气泡覆盖的质量传输效应。测量面向上的p-Si光电阴极在0.50 MH ₂ SO ₄（aq。）中的气体覆盖率，以考虑成核速率和H _2的接触角（g）对于具有各种表面自由能的系统要评估的气泡。在模拟的太阳光照下，小的O ₂（g）气泡迅速离开，在向上生氧的Si光阳极上产生了稳定的光电流，并且相对于停滞的电解质产生了更高的传质速度，这表明气泡可以为太阳能设备中朝上的光阳极的光电化学性能。