Light-Driven Chemical Cascade Reduces Barriers to Hydrogen Production.

Photocatalysis offers an opportunity for sustainable hydrogen and chemical production. Traditional systems require semiconductors with very specific conduction-band (CB) properties and expensive noble metal cocatalysts, limiting material availability and increasing costs. Here, we introduce an alternative photocatalytic pathway that bypasses these constraints, producing hydrogen and formic acid via a cascade process. Under illumination, oxygen and methanol are converted to hydrogen peroxide and formaldehyde, which then react in solution to yield hydrogen and formic acid. We demonstrate the viability of the process employing two limited direct photocatalysts, polymeric carbon nitride (which is not active without a cocatalyst) and tungsten oxide (which presents an unsuitable CB). Our method provides significant advantages: bandgap flexibility, reduced energy consumption and environmental impact, and elimination of noble metal cocatalyst costs. This approach expands the range of suitable semiconductor materials for efficient photocatalytic hydrogen production, offering a more economical and practical solution.