Osaka University researchers have created a new material based on gold and black phosphorus to produce clean hydrogen fuel using the full spectrum of sunlight. Most solar apparatus used in “water splitting” rely on materials such as titanium dioxide. These are limited to obtaining energy from the ultraviolet (UV) part of the solar spectrum, however. The rest of the spectrum is wasted. Osaka’s team “developed a material to harvest a broader spectrum of sunlight,” using a three-part composite. The different parts maximize absorption of light and enhance the efficiency of the unit for water splitting. The core, a “traditional” semiconductor of lanthanum titanium oxide (LTO) is coated with tiny nanoparticle specks of gold. The gold-covered LTO is then mixed with ultrathin sheets of black phosphorus (BP), which acts as a light absorber. Bonding the gold-coated LTO to the BP layer makes a serendipitous combination. Team leader Tetsuro Majima says. “BP is a wonderful material for solar applications because we can …