Photocatalytic selective H2 release from formic acid enabled by CO2 captured carbon nitride

Abstract

Abstract The selective decomposition of formic acid (FA) traditionally needs to be carried out under high temperature with the noble metal-based catalysts. Meanwhile, it also encounters a separation of H2 and CO2 for pure H2 production. The photocatalytic FA dehydrogenation under mild conditions can meet a growing demand for sustainable H2 generation. Here, we reported a photocatalytic selective H2 release from FA decomposition at low temperature for pure H2 production by Pt/g-C3N4. Low-cost and easy-to-obtained urea was utilized to produce carbon nitride as the metal-free semiconductor photocatalyst, along with a photodeposition to obtain Pt/g-C3N4. The electrochemical evidences clearly demonstrate the photocatalytic activity of Pt/g-C3N4 to produce H2 and CO2 in one-step FA decomposition. And, the impedance is the lowest under simulated solar light of 70 mW cm−2 with a faster electron transfer kinetic. Under simulated solar light, H2 production rate is up to 1.59 mmol · h−1 · g−1 for FA with concentration at 2.65 mol l−1, 1700 000 times larger than that under visible light and 1928 times under ultraviolet (UV) light. DFT calculations further elucidate that nitrogen (N) active site at the g-C3N4 has an excellent adsorption towards CO2 molecule capture. Then, H2 molecules are selectively released to simultaneously separate H2 and CO2 in solution. Platinum (Pt) at Pt/g-C3N4 as the catalytic site contributes into the acceleration of H2 production.