# Electricity-free hydrogen production from the air

## TL;DR

A new system produces hydrogen from air moisture without electricity or freshwater, offering a sustainable solution for green hydrogen.

## Contribution

A self-sufficient, electricity-free system for hydrogen production using atmospheric moisture and solar energy is introduced.

## Key findings

- The system achieves a hydrogen production rate of 6467.55 µmol·m-2·h-1 under natural light.
- The system operates without electricity or liquid water, using atmospheric moisture and solar energy.
- The approach is scalable and feasible in regions with suitable humidity and solar conditions.

## Abstract

The ever-growing demand for electricity and clean water restricts widespread application of hydrogen production via water electrolysis or photocatalytic water splitting. Here, we present a self-sufficient electricity-free air-to-hydrogen system that integrates radiative cooling-enhanced water adsorption with synergistic photocatalysis and photothermal conversion by fabricating spectral selective absorbing/emitting hygroscopic hydrogen evolution nanofiber membranes to harvest atmospheric moisture and produce hydrogen. Leveraging the nocturnal radiative cooling effect, we expand the operational relative humidity range of nanofiber membranes and enhance both water collection capacity and kinetics. The collected water undergoes efficient gas-phase water splitting for H2 production during the day through photothermal catalytic processes without electrical and liquid water assistance. The hydrogen production rate of the scale-up air-to-H2 system under outdoor natural light reaches 6467.55 µmol·m-2·h-1. Extrapolating this experimentally validated rate to land-based deployment demonstrates the potential for large-scale hydrogen generation, with practical feasibility dependent on regional humidity and solar conditions. Thus, our approach cost-effectively addresses green-H2 scarcity without demanding natural freshwater and electricity, thereby providing an archetype for global sustainable development.

Rising electricity and freshwater needs limit conventional hydrogen production. Here, the authors report a self-sufficient, electricity-free system that harvests atmospheric moisture to produce green hydrogen, offering a scalable and sustainable path to alleviate global green-hydrogen scarcity.