Halide modification of platinum catalysts enhances efficiency of solar-driven water splitting

Researchers at EPFL's LIMNO laboratory discovered that different halide compounds significantly influence platinum surface chemistry in organic semiconductor photocatalysts used for hydrogen production. By optimizing platinum surfaces with iodide ions, the team achieved a 17% quantum yield at 700 nanometers, among the highest performance levels reported for this material type. These advances could make solar hydrogen production more economically viable for industrial clean energy applications.

Platinum serves as a crucial component in these photocatalytic systems, though researchers have only recently begun understanding how its surface properties affect performance. The study examined three different halide precursor compounds—chlorine, bromine, and iodine variants—discovering that each behaves distinctly during the manufacturing process. Chlorine-based precursors left unwanted residual compounds on the platinum surface that blocked catalytic activity, while iodine-based versions cleaned more thoroughly, enabling superior hydrogen generation rates.

The 17% quantum yield represents a significant milestone in measuring how effectively these materials convert absorbed light into chemical energy at specific wavelengths. This achievement suggests that optimizing co-catalyst chemistry—a design element historically underemphasized in photocatalyst development—may unlock performance improvements across similar systems without requiring entirely new material platforms or expensive alternative elements.