Nonadiabatic Dynamics of Photocatalytic Water Splitting on A Polymeric Semiconductor

Abstract

To elucidate the nature of light-driven photocatalytic water splitting, a polymeric semiconductorgraphitic carbon nitride (g-C3N4)has been chosen as a prototype substrate for studying atomistic water spitting processes in realistic environments. Our nonadiabatic quantum dynamics simulations based on real-time time-dependent density functional theory reveal explicitly the transport channel of photogenerated charge carriers at the g-C3N4/water interface, which shows a strong correlation to bond re-forming. A three-step photoreaction mechanism is proposed, whereas the key roles of hole-driven hydrogen transfer and interfacial water configurations were identified. Immediately following photocatalytic water splitting, atomic pathways for the two dissociated hydrogen atoms approaching each other and forming the H2 gas molecule are demonstrated, while the remanent OH radicals may form intermediate products (e.g., H2O2). These results provide critical new insights for the characterization and further development of efficient water-splitting photocatalysts from a dynamic perspective.

Enhancing mechanism of electron-deficient p states on photocatalytic activity of g-C3N4 for CO2 reduction

“…S12† shows the Gibbs free energy profiles of the HER on the B/N2 V -pg-C 3 N 4 surface. The kinetic barrier of 1.55 eV for the HER of B/N2 V -pg-C 3 N 4 is slightly higher than that of pristine g-C 3 N 4 (1.50 eV) 69 because of the B-induced electronic structure difference. Compared with the optimal products (the energy barriers of HCOOH and HCHO are both 0.86 eV) of CO 2 reduction, the HER side reaction is more difficult to occur on B/N2 V -pg-C 3 N 4 .…”

“…S12 † shows the Gibbs free energy proles of the HER on the B/N2 V -pg-C 3 N 4 surface. The kinetic barrier of 1.55 eV for the HER of B/N2 V -pg-C 3 N 4 is slightly higher than that of pristine g-C 3 N 4 (1.50 eV) 69 because of the B-induced electronic structure difference.…”

Single-atom catalysts for high-efficiency photocatalytic and photoelectrochemical water splitting: distinctive roles, unique fabrication methods and specific design strategies

“…94,95 2.2 The roles and superiority of SACs in photocatalytic and photoelectrochemical water splitting Recently, SACs have attracted rapidly increasing interest for application in photocatalytic and photoelectrochemical water splitting due to their unique merits over NPs and NCs including ultrahigh photo(electro)catalytic activity (abundant active sites), superior stability, stronger surface active site/substrate interaction, improved light-harvesting and charge separation/ transfer capability, easier identication of reaction mechanisms, more obvious structure-activity relationships, etc. 56,[96][97][98][99][100][101][102][103] Based on the working principles of photocatalytic and photoelectrochemical water splitting mentioned above, SACs are regarded as promising photocatalysts (electrodes) compared to their NC, NP and bulk counterparts due to the distinguished roles of SACs in photo(electro)catalysis, which can be mainly described as stronger light-harvesting capability, more efficient charge transfer/separation and more active sites for surface reactions as shown in Fig. 2.…”

Water Oxidation and Hydrogen Evolution with Organic Photooxidants: A Theoretical Perspective

“…On the theoretical side, band structures of periodic models of g-C 3 N 4 have been computed with DFT. − Simulations of the dynamics of photoinduced reaction steps were performed at the DFT level for extended models of g-C 3 N 4 with periodic boundary conditions by Ma and co-workers , and Meng and co-workers . In both simulations, the water oxidation step occurs locally on a Hz building block by H atom transfer from a hydrogen-bonded water molecule to a peripheral N atom of a Hz unit as found in the molecular simulations discussed above.…”