In Situ Engineering of Pd Nanosponge Armored with Graphene Dots Using Br^– toward High-Performance and Stable Electrocatalyst for the Hydrogen Evolution Reaction

Abstract

In this study, we report a facile synthetic pathway to three-dimensional (3D) Pd nanosponge-shaped networks wrapped by graphene dots (Pd@G-NSs), which show superior electrocatalytic activity toward the hydrogen evolution reaction (HER) and exhibited excellent long-term stability in acidic media. Pd@G-NSs were synthesized by simply mixing Pd precursors, reducing agent, carbon dots (Cdots), and Br– ion at 30 °C. Experimental results and density functional theory (DFT) calculations suggested that the Br– ions played an essential role in accelerating the exfoliation of Cdot, supplying graphene layers, which could wrap the nanosponge-shaped Pd and finally form Pd@G-NS. In the absence of the Br– ions, only aggregated Pd nanoparticles (NPs) were formed and randomly mixed with Cdots. The resultant Pd@G-NS exhibited a high electrochemically active surface area and accelerated charge transport characteristics, leading to its superior electrocatalytic activity toward the HER in acidic media. The HER overpotential of Pd@G-NS was 32 mV at 10 mA cm–2, and the Tafel slope was 33 mV dec–1. Furthermore, the unique Pd@G-NS catalyst showed long-term stability for over 3000 cycles in acidic media as well, owing to the protection of Pd nanosponges by graphene dot wrapping. The overall HER performance of the Pd@G-NS catalyst exceeded that of commercial Pt/C.

Data on a highly stable electrocatalyst of NiCoPt/Graphene-dot nanosponge for efficient hydrogen evolution reaction

“…NiCoPt/Graphene-dots (referred to as NiCoPt/G-dot) were synthesized from the mixed precursor solutions and carbon dots (C-dots). C-dots were synthesized using a procedure developed in our previous work [ 2 , 6 , 7 ]. A typical synthesis for the Ni 48 Co 48 Pt 4 /G-dot nanohybrid can be described as seen in Fig.…”

Computational Studies on Carbon Dots Electrocatalysis: A Review

“…The hydrogen bond energy value confirms that the carbon shell of Pd@G-NSs can adjust the binding energy of Pd-H, making the surface of Pd NPs suitable for hydrogen evolution. [102]…”

“…c) Synthesis of two different Pd-based catalysts, energy of CDs exfoliation and average hydrogen binding energy. Reproduced with permission [102]. Copyright 2020, American Chemical Society.…”

Stable Pt atomic clusters on carbon nanotubes grafted with carbon quantum dots as electrocatalyst for H2 evolution in acidic electrolyte

“…Importantly, CQDs have abundant surface/edge sites and excellent electron acceptor/donor capability, which can disperse the atomic metal well and modify their electronic structures. [32][33][34][35] Theoretical calculations showed that CQDs improved the adsorption and dissociation of water molecules on Ru and enhancing electron-transfer ability of catalyst. [32] But the extremely strong hydrophilicity of CQDs restrains its usage in the electrode.…”