In Situ Fabrication of Heterostructure on Nickel Foam with Tuned Composition for Enhancing Water‐Splitting Performance

Abstract

for fossil fuels. Electrocatalytic water splitting is a promising and environmentally friendly approach for the generation of hydrogen gas with high quality and efficiency. [1][2][3][4] However, the electrochemical hydrogen production is seriously limited by the large overpotential and sluggish kinetics of both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). [5][6][7] At present, noble metals (e.g., Pt, Ir, and Ru) based catalysts are regarded as the best electrocatalysts, but their scarcity, high cost, poor stability, and single functionalization for only HER (e.g., Pt) or OER (e.g., Ir, Ru) prevent their widespread commercialization. [8][9][10] Hence, it is highly desirable to develop low-cost and efficient bifunctional electrocatalysts for overall water splitting. [11][12][13] Transition metal chalcogenides (TMCs, M = Fe, Co, Ni, Mn, etc., and C = S, Se) have been extensively explored as electroactive materials to promote HER and OER processes owing to the advantages of cost-effective, high abundance, and intrinsically metallic properties. [14][15][16][17][18][19][20] Recently, the design strategies of highly active TMCs electrocatalysts are mainly focused on following principles: (i) anchoring catalysts on conductive substrates to enable a highly dispersed active species and favor the electron transfer; (ii) engineering micro-nanostructures to Exploiting economical and high-performance bifunctional electrocatalysts toward hydrogen and oxygen evolution reactions (HER/OER) is at the heart of overall water splitting in large-scale application. Herein, an in situ and stepwise strategy for synthesizing core-shell Ni 3 (S 1−x Se x ) 2 @NiOOH (0 ≤ x ≤ 1) nanoarray heterostructures on nickel foam with tailored compositions for enhancing water-splitting performance is reported. A series of Ni 3 (S 1−x Se x ) 2 nanostructures is firstly grown on nickel foam via an in situ reaction in a heated polyol solution system. Ni 3 (S 1−x Se x ) 2 @NiOOH nanocomposites are subsequently prepared via electrochemical oxidation and the oxidation degree is systematically investigated by varying the oxidation time. Benefitting from the vertical standing architecture, abundant exposed active sites, and synergetically interfacial enhancement, Ni 3 (S 0.25 Se 0.75 ) 2 @NiOOH heterojunctions with electrochemical polarization for 8 h exhibit superior HER and OER behaviors, achieving a water-splitting current density of 10 mA cm −2 at a small overpotential of 320 mV as well as boosted reaction kinetics and long-term stability. This work should shed light on the controllable synthesis of metal-based hybrid materials and provide a promising direction for developing the highest-performing electrocatalysts based on interfacial and heterostructural regulation for advanced electrochemical energy conversion technologies. www.small-journal.com electrode to receive stable signals. The HER polarization profiles were performed from 0.1 to −0.8 V, while the OER from 1.0 to 2.0 V at a scan speed of 5 mV s −1 . Elect...

Cobalt Phosphides Nanocrystals Encapsulated by P‐Doped Carbon and Married with P‐Doped Graphene for Overall Water Splitting

“…As shown in Figure E, the CoP‐Co 2 P@PC/PG NHs have the smallest Tafel slope (66 mV dec −1 ), and thereby their OER rate can increase quickly with the increase of potential. It should be mentioned that the OER activity of CoP‐Co 2 P@PC/PG NHs is also superior to CoP‐Co 2 P@PC NHs (Figure S19, Supporting Information), and most of recently reported OER catalysts, such as NiCoP‐NWAs/NF, Co 4 N/CNW/CC, Ni 3 (S 0.25 Se 0.75 ) 2 @NiOOH, and so on. The detailed comparison is given in Table S2 (Supporting Information).…”

Nickel@Nitrogen‐Doped Carbon@MoS2 Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

“…Therefore, many efforts have been devoted to design and fabricate nonprecious metal electrocatalysts for HER. Over the past few years, nonprecious metal–based electrocatalysts such as transition metal sulphides, selenide, nitrides, phosphides, and carbides have been developed as good candidates for HER.…”

Spinel oxide CoFe2O4 grown on Ni foam as an efficient electrocatalyst for oxygen evolution reaction

“…Moreover, the scarcity, high cost and poor durability seriously hamper large-scale application of noble metal-based materials. [12][13][14][15][16][17][18][19] Recently, due to the low cost and earth-abundant reserves, many efforts have been made to develop high activity non-noble metal based electrocatalysts. Non-noble transition metals such as Fe, Co, Ni and Mn have attracted a lot of attention, and the compounds of transition-metals have been suggested as replaceable electrocatalysts in OER.…”