Rapid template‐guided ligand‐free synthesis of ultrasmall Pt nanoclusters with efficient hydrogen evolution reaction activity and their versatile release

Abstract

The design of ligand‐free platinum nanoclusters (PtNCs) for the field of renewable energy is still challenging. Herein, we reported a fast synthesis of ligand‐free Pt nanoclusters (NCs) by utilizing the outer defect of a representative type of zeolitic imidazolate framework (ZIF). Structural investigation suggests a homogenous distribution of the PtNCs on the outer layer of the ZIF‐8 structure. The as‐prepared PtNCs@ZIF‐8 exhibits high catalytic activity for the hydrogen evolution reaction (HER). The extremely low overpotential with 1.4 mV, high kinetic current (specific and mass activity at 50 mV), and larger exchange current density were achieved in acidic solution, better than those of the commercial 20% Pt/C catalysts under the same condition. Furthermore, the PtNCs can be extracted from the ZIF‐8 structure to both aqueous and non‐aqueous solvent, which could be further used for other systems. These findings allow for a simple route of template‐guided NC synthesis and their release.

Structural Analysis and Intrinsic Enzyme Mimicking Activities of Ligand‐Free PtAg Nanoalloys

“…[ 39 ] The XPS spectrum of N 1s for G‐PtAgNCs‐2 and C‐PtAgNPs 4.5 showed a shift to higher binding energy as compared to that in Pt@ZIF‐8 in Figure S13b, Supporting Information and the pristine ZIF‐8. [ 24 ] This implies the existence of an interaction between Pt, Ag with N, and Zn after the introduction of PtAg alloy in ZIF‐8. Notably, the Pt 4f spectrum of G‐PtAgNCs‐2 and C‐PtAgNPs 4.5 had a strong doublet at 70.8 and 74.05 eV for G‐PtAgNCs‐2, while 70.7 and 74.05 eV for C‐PtAgNPs 4.5 are the characteristic peaks of Pt 4f 7/2 and Pt 4f 5/2 , respectively (Figure 3b).…”

“…To synthesize the PtAg nanozymes, two different approaches namely, a) co-reduction and b) a Pt-guided method were carried out (Scheme 1). [24,31] In the co-reduction process K 2 PtCl 4 and AgNO 3 precursors were introduced into the as-obtained ZIF-8 mixture (the experimental details are mentioned in the Supporting Information ) and further reduced by NaBH 4 . For the Pt-guided method, monometallic Pt@ZIF-8 was first formed, followed by the addition of K 2 PtCl 4 and AgNO 3 reduced by NaBH 4 for further PtAg alloy preparation (the details are mentioned in Supporting Information).…”

“…[20][21][22] Ligand-free synthesis has been also achieved by the wetchemical approach by synthesizing the NPs/NCs in a template such as metal-organic frameworks, mesoporous silica, and metal oxides. [23][24][25][26] However, controlling the particle size is one of the major challenges in such template-mediated synthesis.…”

Metal nanocluster‐based devices: Challenges and opportunities

“…[30][31][32][33][34][35] These make NCs suitable candidates in various applications from sensing to photovoltaics. [8,[36][37][38][39][40] Recently, metal NC-sensitized solar cells (MCSCs) have received an increasing attention as emerging photovoltaic devices, possessing similar structure compared to dye-sensitized solar cells (DSSCs). [36,[41][42][43] NPs-based SCs presented limited enhancement in the power conversion efficiency (PCE) because of the possible energy transfer via nonradiative pathway as well as disturbance of the interface morphology.…”