Constructing Ni/NiS Heteronanoparticle-Embedded Metal–Organic Framework-Derived Nanosheets for Enhanced Water-Splitting Catalysis

Abstract

Electrocatalytic water splitting is an emerging technique to produce sustainable hydrogen energy. However, it is still challengeable to fabricate a stable, efficient, and cost-effective electrocatalyst that can overcome the sluggish reaction kinetics of water electrolysis. In order to reduce the energy barrier, for the first time, metal−organic framework (MOF)-derived nickel (Ni) and nickel sulfide (NiS) heteronanoparticleembedded semi-MOFs are prepared by a partial sulfurization strategy. These semi-MOF electrocatalysts inherit the advantages associated with MOF architecture and nanoparticles, unlike the traditional OER catalysts such as pristine MOFs or completely pyrolyzed MOFs. Due to the unique nanoarchitecture fabricated by Ni/NiS heteronanoparticles within semi-MOF nanosheets and a carbon nanotube (CNT) network (Ni-M@C-130), it displays exceptional bifunctional activity over the other transition metalbased electrocatalysts ever reported. It requires very small overpotentials for both oxygen evolution reaction (OER; η 10 = 244 mV) and hydrogen evolution reaction (HER; η 10 = 123 mV), with low Tafel slopes of 47.2 and 50.8 mV/dec, respectively. Furthermore, it exhibits overpotential as low as 1.565 V (η 10 ) on nickel foam (1 mg/cm 2 ) substrates for overall water splitting. The outstanding catalytic performance of Ni-M@C-130 is attributed to the combined benefits of MOF nanosheets, synergistic interactions, and improved electrical conductivity and mechanical stability. This study describes the advantages of partial sulfurization of CNT-integrated MOFs in attaining electrochemically active heteronanoparticles within MOF nanosheets to accomplish improved bifunctional activity.

Fe‐Incorporated Ni3S4/NiS2Nanocomposite as an Efficient Electrocatalyst for Alkaline Water Oxidation

“…This initiated the development of non‐noble metal‐based electrocatalysts with high efficiency, stability and selectivity towards water splitting [7,8] . For the purpose, transition metal (TM)‐based oxides, hydroxides, chalcogenides, metal‐organic frameworks (MOFs), and more are widely explored for OER as well as HER applications [9–21] . Further, much attention was drawn to improve electrocatalysts for OER since it involves more complex four‐electron transfer process [22–24] .…”

“…[7,8] For the purpose, transition metal (TM)-based oxides, hydroxides, chalcogenides, metal-organic frameworks (MOFs), and more are widely explored for OER as well as HER applications. [9][10][11][12][13][14][15][16][17][18][19][20][21] Further, much attention was drawn to improve electrocatalysts for OER since it involves more complex four-electron transfer process. [22][23][24] Among several electrocatalysts, TM-based sulfides are interesting due to high surface area and good conductivity.…”

Design of cobalt‐iron complex sulfides grown on nickel foam modified by reduced graphene oxide as a highly effect bifunctional electrocatalyst for overall water splitting

“…The difference of pH value for electrocatalytic medium takes it a great challenge to combine HER with OER electrocatalysts for water electrolysis 28,29 . Therefore, it is urgent to optimize the water splitting device for the purpose of the bifunctional electrocatalyst which can electrolyze water for both HER and OER at the same time 30‐33 . According to the existing literature reports, Inamdar's group has developed the CuFe bimetallic composite as one of nonprecious, durable and high‐efficient bifunctional electrocatalysts for effective overall water splitting in an alkaline medium.…”

“…28,29 Therefore, it is urgent to optimize the water splitting device for the purpose of the bifunctional electrocatalyst which can electrolyze water for both HER and OER at the same time. [30][31][32][33] According to the existing literature reports, Inamdar's group has developed the CuFe bimetallic composite as one of nonprecious, durable and high-efficient bifunctional electrocatalysts for effective overall water splitting in an alkaline medium. Overpotentials are 218 mV for OER and 158 mV for HER at the current density with 10 mAÁcm À2 , while the potential required for water splitting to engender O 2 and H 2 is 1.64 V at 10 mAÁcm À2 for up to 100 hours of durative long-term operation.…”

Construction of MnxCoyO4/Ti electrocatalysts for efficient bifunctional water splitting

“…With the exploitation of fossil energy reserves and the increasingly serious environmental problems, 1,2 it is urgent to develop clean and sustainable energy to replace the traditional fossil energy. 3,4 Hydrogen energy has many advantages such as high calorific value of combustion, 5 no pollution of combustion products and abundant storage of raw materials; 6,7 therefore, it is considered as an ideal substitute for traditional fossil energy. [8][9][10] However, the slow dynamics cause water to decompose at a voltage higher than the theoretical voltage, requiring additional energy.…”