Solar-Driven Atmospheric Water Production Through Hierarchically Ordered Porous Carbon for Self-Sustaining Green Hydrogen Production.

Green hydrogen production by proton exchange membrane water electrolysis (PEMWE) powered by clean energy is a promising and environmentally friendly technology. However, it relies on a high-purity water source, which is limited in regions facing water scarcity. Here, a coupled self-sustaining solar-enabled system is reported that couples atmospheric water harvesting with PEM water electrolysis (AWH-PEMWE), offering a novel pathway for clean water generation and green hydrogen production. The atmospheric water harvester (AWH) component utilizes N and O co-doped hydrophilic ordered porous carbon, engineered with an interconnected hierarchical porous structure with prosperous channels for efficient mass transport. It enables effective interfacial solar evaporation for water release, achieving a record-high water harvesting capacity of 0.49 L kg^-1 h^-1 at 40% relative humidity (RH). During outdoor tests, the AWH-PEMWE system reaches a peak green hydrogen production rate of 204 mL h^-1 at midday using only atmospheric water as feedstock. Remarkably, the system remains operational under ultra-low humidity conditions down to 20% RH, addressing the challenge of water availability in arid environments. Importantly, the system operates without the need for carrier gases or external energy input accessories, enabling a fully solar-driven process with zero carbon emission throughout the hydrogen production cycle.