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Solar-powered water electrolysis holds significant promise for the mass production of green hydrogen. However, the substantial water consumption associated with electrolysis not only increases the cost of green hydrogen but also raises critical concerns about accelerating water scarcity. Although seawater can serve as an infinite water supply for green hydrogen production, its complex composition poses substantial challenges to efficient and reliable electrolysis. Here, we demonstrate a high-efficiency solar-powered green hydrogen production from seawater. Our approach takes advantage of the full-spectrum utilization of solar energy. Photovoltaic electricity is used to drive the electrolysis, whereas the waste heat from solar cells is harnessed to produce clean water through seawater distillation. With natural sunlight and real seawater as the sole inputs, we experimentally demonstrate a 12.6% solar-to-hydrogen conversion efficiency and a 35.9 L m−2 h−1 production rate of green hydrogen under one-sun illumination, where additional 1.2 L m−2 h−1 clean water is obtained as a byproduct. By reducing reliance on clean water and electricity supplies, this work provides a fully sustainable strategy to access green hydrogen with favorable energy efficiency and technoeconomic feasibility. 

Abstract Here we report a series of nitrogen‐rich conjugated macrocycles that mimic the structure and function of semiconducting 2D metal–organic and covalent organic frameworks while providing greater solution processability and surface tunability. Using a new tetraaminotriphenylene building block that is compatible with both coordination chemistry and dynamic covalent chemistry reactions, we have synthesized two distinct macrocyclic cores containing Ni−N and phenazine‐based linkages, respectively. The fully conjugated macrocycle cores support strong interlayer stacking and accessible nanochannels. For the metal–organic macrocycles, good out‐of‐plane charge transport is preserved, with pressed pellet conductivities of 10⁻³ S/cm for the nickel variants. Finally, using electrochemically mediated CO₂capture as an example, we illustrate how colloidal phenazine‐based organic macrocycles improve electrical contact and active site electrochemical accessibility relative to bulk covalent organic framework powders. Together, these results highlight how simple macrocycles can enable new synthetic directions as well as new applications by combining the properties of crystalline porous frameworks, the processability of nanomaterials, and the precision of molecular synthesis.