Dr. Sam HSU’s paper featured on the back cover of Small Methods

Dr. Sam Hsu’s paper titled “Bandgap Funneling in Bismuth-Based Hybrid Perovskite photocatalyst with efficient Visible-Light-Driven Hydrogen Evolution” has been published (IF: 15.367; DOI: 10.1002/smtd.202200326) and featured as the back cover in Small Methods.

Dr Sam Hsu Small Methods

The photocatalytic system using hydrohalic acid (HX) for hydrogen production is a promising strategy for generating clean and renewable fuels as well as value-added chemicals (such as X2/X 3). A visible-light active and strong-acid resistive photocatalyst is rarely found. Notably, hybrid perovskites have been recognized as a potential photocatalyst for photovoltaic HX splitting. Herein, Dr. Hsu has developed a novel environmentally friendly mixed halide perovskite MA3Bi2Cl9–xIx with a bandgap funnel structure. Because of the gradient neutral formation energy within iodine-doped MA3Bi2Cl9, the concentration of the iodide element decreases from the surface to the interior across the MA3Bi2Cl9–xIx perovskite. The aligned energy levels of iodide/chloride-mixed MA3Bi2Cl9–xIx result in the formation of a graded bandgap funnel structure. This unique structure promotes the photoinduced charge transfer from the interior to the surface, therefore leading to a efficient photocatalytic redox reaction. As a consequence, the anion-exchange technique with the production of the bandgap funnel structure opens up an avenue to design next-generation solar-to-fuel semiconductors for practical applications in the emerging field of energy-generation technology.

Synthetic process hydroiodic acid

Figure. (Left) Synthetic process of all participated samples by adding the varying amount of hydroiodic acid. (right) The energy band diagram of the MA3Bi2Cl9, MA3Bi2Cl9–xIx and MA3Bi2I9.