Merging Single‐Atom‐Dispersed Iron and Graphitic Carbon Nitride to a Joint Electronic System for High‐Efficiency Photocatalytic Hydrogen Evolution

Abstract

Scalable and sustainable solar hydrogen production via photocatalytic water splitting requires extremely active and stable light‐harvesting semiconductors to fulfill the stringent requirements of suitable energy band position and rapid interfacial charge transfer process. Motivated by this point, increasing attention has been given to the development of photocatalysts comprising intimately interfaced photoabsorbers and cocatalysts. Herein, a simple one‐step approach is reported to fabricate a high‐efficiency photocatalytic system, in which single‐site dispersed iron atoms are rationally integrated on the intrinsic structure of the porous crimped graphitic carbon nitride (g‐C3N4) polymer. A detailed analysis of the formation process shows that a stable complex is generated by spontaneously coordinating dicyandiamidine nitrate with iron ions in isopropanol, thus leading to a relatively complicated polycondensation reaction upon thermal treatment. The correlation of experimental and computational results confirms that optimized electronic structures of Fe@g‐C3N4 with an appropriate d‐band position and negatively shifting Fermi level can be achieved, which effectively gains the reducibility of electrons and creates more active sites for the photocatalytic reactions. As a result, the Fe@g‐C3N4 exhibits a highlighted intramolecular synergistic effect, performing greatly enhanced solar‐photon‐driven activities, including excellent photocatalytic hydrogen evolution rate (3390 µmol h−1 g−1, λ > 420 nm) and a reliable apparent quantum efficiency value of 6.89% at 420 nm.

A Tandem 0D/2D/2D NbS2 Quantum Dot/Nb2O5 Nanosheet/g‐C3N4 Flake System with Spatial Charge–Transfer Cascades for Boosting Photocatalytic Hydrogen Evolution

“…As displayed in Figure 4c, the AQE of NSNOCN at 380 ± 10 nm can reach 18.4%, and the AQE at 420 ± 10 nm is as high as 10.8%, far outperforming many g-C 3 N 4 -based photocatalysts including using noble-metal Pt as the cocatalyst in previous reports. [9,[32][33][34][35][36] The cycling stability of H 2 production for NSNOCN was investigated. As shown in Figure 4d, NSNOCN displays a negligible photoactivity loss after seven cycling tests, suggesting excellent stability, as evidenced by the XRD patterns in Figure S7a (Supporting Information), where the XRD patterns of fresh NSNOCN and recycled NSNOCN show no obvious differences.…”

Emerging Metal Single Atoms in Electrocatalysts and Batteries

“…In addition, single-site dispersed Fe atoms were rationally integrated in the porous crimped graphitic carbon nitride (g-C 3 N 4 ) polymer. [136] The as-prepared catalysts showed an appropriate d-band position and negatively shifting Fermi level, which can effectively promote the reducibility of electrons and create more active sites for HER. When served as the electrocatalysts, the material exhibits an excellent HER performance, which is promising for practical applications.…”

“…[130] Besides the carbonaceous materials, inorganic materials, such as MoS 2 nanosheets, were applied as the support for Ni SAs, and the final composited Ni SAs-MoS 2 electrocatalysts can display very high activity toward HER. [131] Other metal SAs, including molybdenum (Mo), [132,133] tungsten (W), [134] Cu, [135] and Fe, [136] were also designed and constructed. For the first time, Li et al prepared the Mo SAs supported on N-doped carbon material via the template and pyrolysis method, using sodium molybdate and chitosan as precursors.…”

“…For the first time, Li et al prepared the Mo SAs supported on N-doped carbon material via the template and pyrolysis method, using sodium molybdate and chitosan as precursors. [132] The local atomic structure of the catalyst was Porous structure -High stability [136] confirmed to be the MoNC 2 moiety, and the as-prepared electrocatalysts exhibited high activity for HER in the alkaline condition. Moreover, a single-W-atom catalyst loaded on MOF-derived N-doped carbonaceous materials was reported for efficient electrochemical HER, along with high activity and excellent stability.…”

Single Metal Atom Decorated Carbon Nitride for Efficient Photocatalysis: Synthesis, Structure, and Applications

“…Specifically, the lone electron pairs of N atoms are able to bind with SMAs with empty or partially filled orbitals. Therefore, the construction of photocatalysts with metals, such as Pd, [ 11–14 ] Pt, [ 15–17 ] Au, [ 18–22 ] Ag, [ 23,24 ] Co, [ 25–27 ] Fe, [ 28,29 ] Cu, [ 30–35 ] and Mn, [ 36 ] atomically dispersed on g‐C 3 N 4 has become highly anticipated. These SMAs are reactive themselves and therefore can increase the number of active centers tremendously, [ 37–46 ] giving rise to a new type of heterogeneous catalysis that is often referred to as SMA photocatalysis.…”