Photoelectrochemical water splitting is an attractive solar-to-hydrogen pathway. However, the lifetime of photoelectrochemical devices is hampered by severe photocorrosion of semiconductors and instability of co-catalysts. Here we report a strategy for stabilizing photoelectrochemical devices that use a polyacrylamide hydrogel as a highly permeable and transparent device-on-top protector. A hydrogel-protected Sb₂Se₃ photocathode exhibits stability over 100 h, maintaining ~70% of the initial photocurrent, and the degradation rate gradually decreases to the saturation level. The structural stability of a Pt/TiO₂/Sb₂Se₃ photocathode remains unchanged beyond this duration, and effective bubble escape is ensured through the micro gas tunnel formed in the hydrogel to achieve a mechanically stable protector. We demonstrate the versatility of the device-on-top hydrogel protector under a wide electrolyte pH range and by using a SnS photocathode and a BiVO₄ photoanode with ~500 h of lifetime.

光电化学水分解是一种有吸引力的太阳能制氢途径。然而，光电化学器件的寿命受到半导体严重光腐蚀和助催化剂不稳定性的阻碍。在这里，我们报告了一种稳定光电化学设备的策略，该设备使用聚丙烯酰胺水凝胶作为高渗透性和透明的设备顶部保护器。水凝胶保护的 Sb ₂ Se ₃光阴极在 100 小时内表现出稳定性，保持初始光电流的约 70%，并且降解速率逐渐降低至饱和水平。Pt/TiO ₂ /Sb ₂ Se _{3的结构稳定性}超过此时间后，光电阴极保持不变，通过水凝胶中形成的微气体隧道确保有效的气泡逸出，从而实现机械稳定的保护器。我们通过使用寿命约为 500 小时的SnS 光电阴极和 BiVO ₄光电阳极，展示了设备顶部水凝胶保护器在宽电解质 pH 范围内的多功能性。