Nanoscale Self‐Wetting Driven Monatomization of Ag Nanoparticle for Excellent Photocatalytic Hydrogen Evolution

Abstract

Metal nanoparticles (NPs) with <10 nm have demonstrated many novel applications including surprisingly low melting point, astonishing liquidlike pseudoelasticity, and outstanding hydrogen evolution performance. Here, a nanoscale self-wetting driven monatomization of Ag NPs with <5 nm on carbon nitride (CN) to fabricate Ag single-atom catalyst (Ag 1 /CN SAC) is demonstrated, and a thermodynamic approach to elucidate Ag NPs decomposing into single atoms is established. Dynamic dispersion process of Ag NPs into atoms on CN is recorded using in situ AC-HADDF-TEM techniques. Density functional theory calculations and molecular dynamics simulations suggest that the spontaneous dispersion origins from the nanoscale self-wetting effect in thermodynamics. In atomic scale, the driving force of self-wetting derived from the balance between cohesive energy of Ag NPs and excess energy of Ag atoms in CN vacations. The fabricated Ag 1 /CN SAC proved a higher efficiency for photocatalytic hydrogen evolution activity (3690 μmmol g −1 h −1 ) than Pt nanoparticles on CN (3192 μmmol g −1 h −1 ). This spontaneous monatomization resulting from the interaction between metal NPs and substrate provides a simple method to prepare SACs with a high active photocatalytic hydrogen evolution.

Carbon nitride based materials: more than just a support for single-atom catalysis

“…[381][382][383][384] An unconventional metal precursor was used by Yan et al in a top-down synthetic strategy towards Ag single-atoms. 385 In particular, 5 nm of Ag NPs were mixed with CN in an aqueous suspension. After calcination at 350 1C, the authors observed that most metallic nanoparticles were broken down into individual atoms, i.e.…”

Recent Progress of Single‐Atom Photocatalysts Applied in Energy Conversion and Environmental Protection

“…Yan et al annealed the prepared Ag NPs@CN at 300 °C to convert Ag NPs into Ag SAs spontaneously. [ 90 ] Figure a recorded the nanoscale self‐wetting spontaneous atomic dispersion of Ag NPs on CN. The thermodynamics and dynamics of the process were simulated and calculated by MD and DFT (Figure 2b–d).…”

“…Reproduced with permission. [ 90 ] Copyright 2022, Wiley‐VCH. e) The evolution of PdNP to PdPNP and PdPSA.…”

“…c) DFT calculations.d) The corresponding total energy of c). Reproduced with permission [90]. Copyright 2022, Wiley-VCH.…”

Electronic modulation of NiO by constructing an amorphous/crystalline heterophase to improve photocatalytic hydrogen evolution

“…[3][4][5][6] Charge separation, transportation and optical performance are essential to the potential of semiconductors in HER applications. [7][8][9] Nevertheless, the lack of active sites with suitable adsorption energy, the rapid recombination of photogenerated charge carriers and the low utilization ratio of visible light are obstacles to the practical application of semiconductor photocatalysts in photocatalytic H 2 generation. 10,11 Modication with cocatalysts, such as noble metals, 12 metal oxides, 13,14 metal suldes, 15,16 metal compounds [17][18][19] and metal-free compounds, 20,21 has been considered as a rational way to improve the photocatalytic activity by providing effective active sites for favorable proton adsorption and hydrogen desorption, along with assistance in electron transfer and inhibition of the rapid charge recombination.…”