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

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.

Hydrogen production from chemical hydrogen storage materials over copper‐based catalysts

“…Presently, Pd is recognized as the most efficient metal for FAD. [345][346][347][348][349][350][351][352][353][354][355][356][357][358][359][360][361] Other metal catalysts, such as Pt, [362][363][364][365][366][367][368][369] Au, [370][371][372][373][374][375][376][377][378][379][380][381] Cu, 382 Co, [383][384][385][386][387] and Ni 388,389 have also been extensively studied, although not as active as Pd catalysts.…”

“…Presently, Pd is recognized as the most efficient metal for FAD 345–361 . Other metal catalysts, such as Pt, 362–369 Au, 370–381 Cu, 382 Co, 383–387 and Ni 388,389 have also been extensively studied, although not as active as Pd catalysts.…”

Quantum yield enhancement in the photocatalytic HCOOH decomposition to H2 under periodic illumination

“…68,69 Meanwhile, increasing R CT of the mobile photogenerated electrons on the catalyst surface appears to improve the reaction quantum yield for H 2 evolution although the reverse trend is commonly speculated in the literature. 43,[70][71][72][73]…”

Selective Photocatalytic Dehydrogenation of Formic Acid on Graphite Carbon Nitride with Dual-Sited Cobalt and Platinum Cocatalysts

“…Up to now, many photocatalysts have been developed to realize the photocatalytic hydrogen evolution from the FA dehydrogenation process. Metal sulfides with great visible light absorption show high efficiency in photocatalytic dehydrogenation of FA. − However, the serious photocorrosion and H 2 S formation greatly reduce the feasibility of this process in the large-scale application. , Graphite carbon nitride (g-C 3 N 4 ) with prominent advantages in visible light absorption, low cost, nontoxicity, and easy fabrication shows a potential in photocatalytic hydrogen generation from FA dehydrogenation. − In order to overcome the intrinsic drawbacks of pristine g-C 3 N 4 , many strategies have been developed including the formation of hetero/homojunction, defect regulation, crystalline engineering, and so forth to extend the light absorption region and improve charge separation. − The oriented modification of g-C 3 N 4 for photocatalytic FA dehydrogenation should take the basic reaction pathway into consideration, which first involves the proton release from FA by photogenerated holes and then follows the proton reduction by photogenerated electrons . Therefore, the rational design of g-C 3 N 4 -based photocatalysts with dual functionality is highly desired for photocatalytic hydrogen production from the selective FA dehydrogenation process.…”