Solar-driven water splitting is an emerging technology with high potential to generate fuel cleanly and sustainably. In this work, we show that WO₃ can be used as a cathodic electrocatalyst in combination with (Ag,Cu)InGaSe₂ solar cell modules to produce hydrogen and provide electrochromic functionality to water splitting devices. This electrochromic effect can be used to monitor the charge state or performance of the catalyst for process control or for controlling the temperature and absorbed heat due to tunable optical modulation of the electrocatalyst. WO₃ films coated on Ni foam, using a wide range of different sputtering conditions, were investigated as cathodic electrocatalysts for the water splitting reaction. The solar-to-hydrogen ($\mathit{STH}$) efficiency of solar-driven water electrolysis was extracted using (Ag,Cu)InGaSe₂ solar cell modules with a cell band gap varied in between 1.15 and 1.25 eV with WO₃ on Ni foam-based electrolyzers and yielded up to 13% $\mathit{STH}$ efficiency. Electrochromic properties during water electrolysis were characterized for the WO₃ films on transparent substrate (indium tin oxide). Transmittance varied between 10% and 78% and the coloration efficiency at a wavelength of 528 nm and the overpotential of 400 mV was 40 cm² C⁻¹. Hydrogen ion consumption in ion intercalation for electrochromic and hydrogen gas production for water electrolysis processes was discussed.

太阳能驱动的水分解是一种新兴技术，具有清洁，可持续地产生燃料的潜力。在这项工作中，我们表明WO ₃可以与（Ag，Cu）InGaSe ₂太阳能电池模块结合用作阴极电催化剂，以产生氢并为水分解装置提供电致变色功能。该电致变色效应可用于监视催化剂的电荷状态或性能，以进行过程控制或由于电催化剂的可调光调制而控制温度和吸收的热量。研究了使用多种不同的溅射条件在Ni泡沫上涂覆的WO ₃膜作为水分解反应的阴极电催化剂。太阳到氢（$\mathit{STH}$）使用（Ag，Cu）InGaSe ₂太阳能电池组件提取太阳能驱动水的效率，该电池组件的带隙在Ni泡沫基电解槽上与WO ₃一起在1.15和1.25 eV之间变化，且产率高达13％$\mathit{STH}$效率。对水在电解过程中的电致变色特性进行了表征，该WO ₃膜位于透明基材（氧化铟锡）上。透射率在10％至78％之间变化，并且在528nm的波长和400mV的过电势下的着色效率为40cm ² C ^-1。讨论了电致变色离子插层中的氢离子消耗量以及水电解过程中的氢气产生量。