Materials Chemistry Group, Department of Chemical Sciences, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400005, India.
ACS Appl Mater Interfaces. 2023 Jan 11;15(1):1219-1226. doi: 10.1021/acsami.2c17919. Epub 2022 Dec 23.
Photocatalytic (PC) hydrogen production from water splitting is a promising route to fulfill the current energy demand in a sustainable manner. For photocatalysis to become industrially viable, seawater should be used as an ideal solvent. Until now, a variety of semiconductor photocatalysts have been exploited for seawater splitting; however, there has been a lack of a well-established catalytic system for seawater splitting, as seawater ions have an uncertain effect on water splitting. Recently, ionized carbon nitride PC has been shown to substantially enhance water splitting in the presence of ions; however, the underlying manner by which the ions promote PC has still not been fully understood. Presented here is a systematic evaluation of an ionized low-cost carbon nitride-based semiconductor for seawater splitting. A detailed study has been done using this salt-type semiconductor in the presence of a variety of ions (Na, K, Mg, Ca, Cl, SO), and their role has been probed in modulating the photocatalytic activity. Multiple measurements have provided insight as to how the presence of cations aid advantageously in forming an effective interface between catalyst/cocatalyst for improved electron transfer. Previously, these ions were purported to change the hole quenching ability only of the photocatalyst, whereas here it has been shown that the change in the electron transfer ability of the photocatalyst to cocatalyst appears to be the cause for augmented PC. This improved interfacial electron transfer has been used to rationalize the 8-fold enhancement in the photocatalytic rate in the presence of simulated seawater compared to deionized water and provides the impetus for the use of ionized carbon nitride structures for sustainable PC splitting of seawater.
光催化（PC）水分解制氢是一种有前途的方法，可以以可持续的方式满足当前的能源需求。为了使光催化在工业上可行，应该使用海水作为理想的溶剂。到目前为止，已经开发了各种半导体光催化剂用于海水分解；然而，由于海水离子对水分解的影响不确定，因此缺乏完善的海水分解催化体系。最近，已经证明离子化氮化碳 PC 可以在存在离子的情况下大大增强水分解；然而，离子促进 PC 的基本方式仍未完全理解。本文对基于离子化氮化碳的低成本半导体在海水中分解进行了系统评价。在存在各种离子（Na、K、Mg、Ca、Cl、SO）的情况下，对这种盐型半导体进行了详细研究，并探讨了它们在调节光催化活性方面的作用。多项测量提供了深入了解阳离子如何有利于在催化剂/共催化剂之间形成有效的界面，从而促进电子转移。以前，这些离子据说是仅改变光催化剂的空穴猝灭能力，而在这里，已经表明光催化剂到共催化剂的电子转移能力的变化似乎是增强 PC 的原因。这种改进的界面电子转移已被用于合理化在模拟海水中存在时光催化速率提高了 8 倍，与去离子水相比，这为使用离子化氮化碳结构进行可持续的海水 PC 分解提供了动力。
