Polyureas have widespread applications due to their unique material properties. Because of the toxicity of isocyanates, sustainable isocyanate-free routes to prepare polyureas are a field of active research. Current routes to isocyanate-free polyureas focus on constructing the urea moiety in the final polymerizing step. In this study we present a new isocyanate-free method to produce polyureas by Ru-catalyzed carbene insertion into the N–H bonds of urea itself in combination with a series of bis-diazo compounds as carbene precursors. The mechanism was investigated by kinetics and DFT studies, revealing the rate-determining step to be nucleophilic attack on a Ru–carbene moiety by urea. This study paves the way to use transition-metal-catalyzed reactions in alternative routes to polyureas.

Hematite as a sustainable photoabsorber material offers a band gap close to 2 eV and photoanode characteristics, but usually requires additional catalysts to enhance surface redox chemistry during steady state light energy harvesting for water splitting. Here, for a highly doped hematite film, sufficient intrinsic photocapacitor behavior is reported for the conversion of light transients into energy. Residual energy is harvested in a symmetric architecture with two opposing mesoporous hematite films on conductive glass. Transient light energy harvesting is shown to occur without the need for water splitting.

Polyureas have widespread applications due to their unique material properties. Due to the toxicity of isocyanates, sus-tainable isocyanate-free routes to prepare polyureas is a field of active research. Current routes to isocyanate-free poly-ureas focus on constructing the urea moiety in the final polymerizing step. In this study we present a new isocyanate-free method to produce polyureas by Ru-catalyzed carbene insertion into the N‒H bonds of urea itself in combination with a series of bis-diazo compounds as carbene precursors. The mechanism was investigated by kinetics and DFT studies, re-vealing the rate determining step to be nucleophilic attack of a Ru-carbene moiety by urea. This study paves the way to use transition-metal catalyzed reactions in alternative routes to polyureas.