Low-Pt coupled with atomic Ni-N5 doped carbon dots as efficient ORR/HER bifunctional catalyst

Constructing supported catalysts is an effective means to address the critical yet challenging issue of reducing platinum (Pt) usage while remaining its catalytic activity and stability. The marked effect of the support's physicochemical properties on the catalytic activity of the loaded Pt mandates an elaborate design and regulation to carbon carriers. Herein, we provide a simple and eco-friendly approach to prepare carbon dots support material with plenty of defect structure and atomically dispersed Ni-N 5 sites (Ni-NC), using non-toxic chitosan as precursor. This material was further utilized to anchor Pt to achieve NiPt-NC electrocatalyst with highly dispersed Pt nanoparticles (NPs) (∼2 nm) and low Pt loading (2.49 wt%). The Experimental and theoretical calculation results illustrate that the interaction between Pt NPs and surrounding Ni-N 5 sites leads to the electron enrichment around Pt, which not only optimizes the desorption of ∗OH and adsorption/dissociation of H 2 O (Volmer step), therefore improving the intrinsic activity of Pt for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER), but also effectively enhances its catalytic stability. Especially, in practical rechargeable Zn-air batteries (RZABs) tests, NiPt-NC acheives a power density of 176 mW cm - 2 and sustains a cycling stability of 160 h. Furthermore, a water electrolysis cell assembled with NiPt-NC displays a current density of 10 mA cm - 2 at a voltage of merely 1.50 V, and maintains a current density of 20 mA cm - 2 without significant degradation for 30 h. The superior catalytic properties of NiPt-NC underscore its promising potential for application in practical devices. Enhanced metal-support interactions between Low-loading platinum and Ni–N 5 rich carbon lead to a bifunctional performance of HER and ORR. • Carbon dots with atomic Ni–N 5 site (Ni-NC) is prepared by a simple and green route. • Pt and Ni-NC couple to construct a NiPt-NC electrocatalyst with low Pt usage. • The metal-supports interaction optimizes the electronic/geometric structure of Pt. • NiPt-NC exhibits decent ORR/HER bifunctional catalytic activity and stability. • NiPt-NC demonstrates application potential in practical energy storage devices.