Fe‐Doped Ni₃C Nanodots in N‐Doped Carbon Nanosheets for Efficient Hydrogen‐Evolution and Oxygen‐Evolution Electrocatalysis

Abstract

Uniform Ni 3 Cn anodots dispersed in ultrathin Ndoped carbon nanosheets were successfully prepared by carburization of the two dimensional (2D) nickel cyanide coordination polymer precursors.T he Ni 3 Cb ased nanosheets have lateral length of about 200 nm and thickness of 10 nm. When doped with Fe,t he Ni 3 Cb ased nanosheets exhibited outstanding electrocatalytic properties for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Fore xample,2at %F e( atomic percent) doped Ni 3 C nanosheets depict al ow overpotential (292 mV) and as mall Tafel slope (41.3 mV dec À1 )f or HER in KOHs olution. An outstanding OER catalytic property is also achieved with alow overpotential of 275 mV and asmall Tafel slope of 62 mV dec À1 in KOHs olution. Suchn anodot-incorporated 2D hybrid structures can serve as an efficient bifunctional electrocatalyst for overall water splitting.Asanideal alternative for fossil fuel, hydrogen energy has aroused great research interest in the past few years.Among various methods for the preparation of low-price and highly purified hydrogen, electrochemical water splitting is one of the most attractive methods. [1] Theoxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are two important half reactions involved in electrochemical water splitting. [2] Unfortunately,both OER and HER are kinetically sluggish, which require highly active electrocatalysts to expedite the process.N oble-metal-based catalysts,i ncluding Pt, RuO 2 ,and IrO 2 ,can efficiently reduce the energy barrier and thus increase the OER or HER efficiency,w hile their large-scale applications are still hindered by their high cost and earth scarcity. [3] Therefore,t he development of alternative non-noble metal catalysts with low-cost and earth abundance has become ag reat challenge for the HER or OER. Tremendous research efforts have been devoted to exploring inexpensive,e fficient, and durable non-precious electrocatalysts,i ncluding metals, [4] alloys, [5] metal oxides, [6] metal nitrides, [7] metal sulfides, [8] metal selenides, [9] metal carbides, [10] and metal hydroxides. [11] However, development of bifunctional electrocatalysts with effective both HER and OER properties is still abig challenge.Since the innovative report of tungsten carbide used as effective catalyst, transition-metal carbides (TMCs) have recently received great research interest owing to their many outstanding properties,i ncluding high electrical and thermal conductivities,h igh melting point, excellent mechanical strength and hardness,a nd also their chemical stabilities along with the resistance against corrosion. [12] Owing to their special simple metallic structures with small carbon atoms in the interstitial voids of the densely packed host lattice,TMCs are endowed with the interstitial alloy properties and have attracted considerable attention in catalytic and electrochemical fields. [13] To date,m olybdenum carbides (Mo 2 C), tungsten carbide (WC), vanadium carbide (V 2 C), and titanium carbide (Ti 2 C) hav...

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