CO ₂ ‐Free Formaldehyde Electro‐Reforming Fuel Cell

ABSTRACT

Conventional electrochemical synthesis is often hampered by steep energy demands and catalyst degradation, limiting both efficiency and durability. Here we introduce a hybrid alkali/acid formaldehyde‐to‐hydrogen fuel cell (h‐A/AFHFC) that transcends these limitations by coupling alkaline formaldehyde oxidation conversion with acidic oxygen reduction. A columnar branched AgCu catalyst drives the h‐A/AFHFC to a striking 2.0 V output and peak power density of 482 mW cm ⁻² , maintaining robust operation for over 110 h. Beyond electricity, the device leverages the exceptionally low oxidation potential of formaldehyde and its single‐electron dehydrogenation pathway to co‐produce hydrogen and formate in a *CO‐free, CO ₂ ‐free electrochemical process, reformulating the role of fuel cells. Each kilogram of hydrogen is inherently paired with 46.0 kg of formate and 33.2 kWh of electricity, offering a rare convergence of clean energy and high‐value chemical synthesis. This strategy extends to gaseous formaldehyde and diverse aldehydes, enabling integrated energy‐chemical platforms for sustainability.