Artificial photosynthesis, which combines photocatalytic CO₂ reduction with water oxidation to produce carbon-based fuels and feedstocks, has gained extensive interest nowadays. To optimize this system, a synergistic promotion of CO₂ reduction and water oxidation is required. However, an obstacle to achieving this synergy is the contradiction in the preferred reaction environments between CO₂ reduction (preferring a gas–solid environment) and water oxidation (preferring a water–solid environment). To address this challenge, we have developed a floatable catalyst by sequentially layering Cu₂O, Ag and TiO₂ on a PTFE membrane support. When this catalyst floats on the gas–water boundary and is illuminated, oriented charge separation occurs across the membrane and the tri-phase (gas–water–solid) interface. Photogenerated electrons accumulate on the side of the membrane exposed to the gas phase, initiating gas–solid CO₂ reduction. Simultaneously, holes transfer to the side immersed in water, facilitating water–solid water oxidation. This design enhances the production rate by 120 fold and 10 fold for CO₂ reduction and water oxidation to H₂O₂ at most, and selectivity by up to 105 times and 2 times for these two half-reactions at most, when compared to a conventional gas–solid or water–solid system, or a tri-phase system on a catalyst without oriented charge separation. Distinctive to the generally considered catalyst-centered strategies, this study provides a new insight to optimize photocatalysis through the regulation of the reaction environment.

中文翻译：

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一种可漂浮的光催化剂，通过在三相界面上产生定向电荷分离，协同促进二氧化碳还原和水氧化


人工光合作用将光催化 CO ₂ 还原与水氧化相结合来生产碳基燃料和原料，目前已引起广泛关注。为了优化该系统，需要协同促进 CO ₂ 还原和水氧化。然而，实现这种协同作用的一个障碍是CO ₂ 还原（优选气固环境）和水氧化（优选水固环境）之间的优选反应环境之间的矛盾。为了应对这一挑战，我们通过在 PTFE 膜载体上顺序分层 Cu ₂ O、Ag 和 TiO ₂ 开发了一种可漂浮催化剂。当该催化剂漂浮在气-水边界上并被照射时，跨膜和三相（气-水-固）界面发生定向电荷分离。光生电子积聚在暴露于气相的膜一侧，引发气固 CO ₂ 还原。同时，空穴转移到浸入水中的一侧，促进水-固水氧化。该设计将 CO ₂ 还原和水氧化为 H ₂ O ₂ 的产率最多提高了 120 倍和 10 倍，选择性高达与传统的气-固或水-固体系或没有定向电荷分离的催化剂上的三相体系相比，这两个半反应最多分别为105倍和2倍。与通常认为的以催化剂为中心的策略不同，这项研究提供了通过调节反应环境来优化光催化的新见解。