Hierarchical Oriented Metal–Organic Frameworks Assemblies for Water‐Evaporation Induced Electricity Generation

Advances in metal–organic frameworks (MOFs) are stimulating interest in water‐evaporation induced electricity generation. Establishing design principles for desirable MOFs and revealing the structure‐activity relationship is essential to development of this field. Around this key issue, herein the concept of “hierarchical oriented MOFs” is proposed and the Cu(BDC‐OH) MOFs are organized into hierarchical oriented assemblies by successively using methods of hydrolysis, anion exchange reaction, and heteroepitaxy growth. It is discovered that this hierarchical oriented Cu(BDC‐OH) assemblies‐based generator containing long‐ranged ordered microporous channels exhibits a voltage of 0.6 V and electricity output of 1.56 nW cm–2 in the natural state of water evaporation. Finite element analysis and density functional calculation elucidate that hierarchical oriented structure of Cu(BDC‐OH) MOFs with certain surface charge density have an “aggregation effect,” dominating the final output voltages. This work not only offers valuable theoretical guidance for exploring self‐assembly of MOFs superstructures and water‐evaporation induced electricity generation, but also may open interesting perspectives for understanding some fundamental questions about structure‐activity relationship in MOFs materials science. A type of bamboo raft‐like Cu(BDC‐OH) metal–organic frameworks is designed for water‐evaporation induced electricity generation. The effect of hierarchical oriented assemblies and coordination structures of Cu(BDC‐OH) in water‐evaporation induced electricity generation is studied.