# Upcycling Wood Waste into Solar-Driven Regenerative Sorbent for Direct Air Capture

## TL;DR

This paper presents a method to convert wood waste into a solar-powered CO2 capture material, offering a sustainable and energy-efficient solution for direct air capture.

## Contribution

The novel approach uses wood waste with preserved lignin for solar-driven CO2 adsorbent regeneration without additional photothermal fillers.

## Key findings

- The adsorbent achieves a CO2 uptake of 1.84 mmol/g at 25°C.
- It releases 50% of CO2 in 22 minutes at 67°C under solar illumination.
- Water vapor enhances CO2 adsorption capacity, especially in humid conditions.

## Abstract

Direct air capture (DAC) is a promising negative-emission
technology
for mitigating climate change caused by excessive atmospheric CO2 emissions. Amine-functionalized solid adsorbents exhibit
a strong affinity for CO2 in ambient air, making them attractive
for DAC systems. However, their regeneration for reuse typically requires
a high energy use during thermal swing processes. Herein, we upcycle
wood waste into a DAC adsorbent that can release CO2 via
solar light irradiation for an energy-saving DAC process. Importantly,
the as-synthesized adsorbent in situ preserves lignin,
enabling photothermal heating without addition of photothermal fillers
into a complex composite. The as-synthesized adsorbent exhibits a
CO2 uptake of 1.84 mmol/g at 25 °C, rapidly reaching
50% of its capacity within 7 min, and releasing 50% of CO2 in 22 min at 67 °C under solar illumination. Moreover, this
study found the presence of water vapor enhances the CO2 adsorption capacity of the adsorbent, making it particularly advantageous
for CO2 capture under humid air conditions. This work demonstrates
a straightforward approach for developing solar-driven regenerative
CO2 adsorbents based to a large fraction on waste lignocellulosic
biomass, offering a promising pathway to sustainable and energy-efficient
DAC.