Overall Water Splitting Catalyzed Efficiently by an Ultrathin Nanosheet‐Built, Hollow Ni₃S₂‐Based Electrocatalyst

Abstract

Making highly efficient catalysts for an overall ​water splitting reaction is vitally important to bring solar/electrical‐to‐hydrogen energy conversion processes into reality. Herein, the synthesis of ultrathin nanosheet‐based, hollow MoOx/Ni3S2 composite microsphere catalysts on nickel foam, using ammonium molybdate as a precursor and the triblock copolymer pluronic P123 as a structure‐directing agent is reported. It is also shown that the resulting materials can serve as bifunctional, non‐noble metal electrocatalysts with high activity and stability for the hydrogen evolution reaction (HER) as well as the oxygen evolution reaction (OER). Thanks to their unique structural features, the materials give an impressive water‐splitting current density of 10 mA cm−2 at ≈1.45 V with remarkable durability for >100 h when used as catalysts both at the cathode and the anode sides of an alkaline electrolyzer. This performance for an overall water splitting reaction is better than even those obtained with an electrolyzer consisting of noble metal‐based Pt/C and IrOx/C catalytic couple—the benchmark catalysts for HER and OER, respectively.

Retracted: Earth‐Abundant Iron Diboride (FeB2) Nanoparticles as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting

“…The Tafel slope of 52.7 mV dec −1 for benchmark Pt/C is consistent with the value reported in the literature . FeB 2 exhibits a Tafel plot of a slope of 87.5 mV dec −1 , larger than that of Pt/C, but comparable or superior to that of many earth‐abundant HER catalysts reported recently, such as Co 2 B‐500/NG (92.4 mV dec −1 ), Ni–B x (88 mV dec −1 ), Cu 3 P‐550 (105 mV dec −1 ), h‐NiS x (99 mV dec −1 ), and MoO x /Ni 3 S 2 /NF (90 mV dec −1 ) . Generally, the HER pathway in alkaline electrolyte follows the Volmer–Heyrovsky or Volmer–Tafel mechanisms shown in Equations and …”

Retracted: Earth‐Abundant Iron Diboride (FeB2) Nanoparticles as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting

“…The Tafel slope of 52.7 mV dec −1 for benchmark Pt/C is consistent with the value reported in the literature . FeB 2 exhibits a Tafel plot of a slope of 87.5 mV dec −1 , larger than that of Pt/C, but comparable or superior to that of many earth‐abundant HER catalysts reported recently, such as Co 2 B‐500/NG (92.4 mV dec −1 ), Ni–B x (88 mV dec −1 ), Cu 3 P‐550 (105 mV dec −1 ), h‐NiS x (99 mV dec −1 ), and MoO x /Ni 3 S 2 /NF (90 mV dec −1 ) . Generally, the HER pathway in alkaline electrolyte follows the Volmer–Heyrovsky or Volmer–Tafel mechanisms shown in Equations and …”

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting

“…The high HER performance illustrated here and the excellent OER activity proposed above indicate that the Ni 1 /β 12 -BM is a promising bifunctional catalyst for the overall water splitting. It is worth noting that most of recent produced bifuncational electrocatalysts for the overall water splitting are also Ni-based materials (nickel phosphides, nitrides, sulfides, and oxides), − ,,− in line with our results that Ni 1 /β 12 -BM is active for both HER and OER, whereas other β 12 -BM based SACs are not. We conclude that the Ni 1 /β 12 -BM is a promising bifunctional SAC.…”

Hierarchical MoP Hollow Nanospheres Anchored on a N,P,S‐Doped Porous Carbon Matrix as Efficient Electrocatalysts for the Hydrogen Evolution Reaction

“…[51,52] The concave curvesf or Mo and Pi nt he energy dispersive spectroscopy line-scanp rofile also confirm the hollow structure ( Figure S4 in the Supporting Information), which has been demonstrated to be ad esired architecture for the efficient HER. [53][54][55][56] As shown in Figure4d, two sets of lattice fringes with d-spacings of about 0.21 and 0.28 nm refer to the (1 01)a nd (1 00)p lanes of the MoP phase, in good accordance with the XRD results. More interestingly,t he hollow nanospheres are composed of numerous randomly but tightly intertwined MoP subunits, along with some shrunken ones displaying this feature ( Figure S5 in the Supporting Information).…”

Retracted: Earth‐Abundant Iron Diboride (FeB2) Nanoparticles as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting

“…The Tafel slope of 52.7 mV dec −1 for benchmark Pt/C is consistent with the value reported in the literature . FeB 2 exhibits a Tafel plot of a slope of 87.5 mV dec −1 , larger than that of Pt/C, but comparable or superior to that of many earth‐abundant HER catalysts reported recently, such as Co 2 B‐500/NG (92.4 mV dec −1 ), Ni–B x (88 mV dec −1 ), Cu 3 P‐550 (105 mV dec −1 ), h‐NiS x (99 mV dec −1 ), and MoO x /Ni 3 S 2 /NF (90 mV dec −1 ) . Generally, the HER pathway in alkaline electrolyte follows the Volmer–Heyrovsky or Volmer–Tafel mechanisms shown in Equations and …”

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting

“…The high HER performance illustrated here and the excellent OER activity proposed above indicate that the Ni 1 /β 12 -BM is a promising bifunctional catalyst for the overall water splitting. It is worth noting that most of recent produced bifuncational electrocatalysts for the overall water splitting are also Ni-based materials (nickel phosphides, nitrides, sulfides, and oxides), − ,,− in line with our results that Ni 1 /β 12 -BM is active for both HER and OER, whereas other β 12 -BM based SACs are not. We conclude that the Ni 1 /β 12 -BM is a promising bifunctional SAC.…”

Hierarchical MoP Hollow Nanospheres Anchored on a N,P,S‐Doped Porous Carbon Matrix as Efficient Electrocatalysts for the Hydrogen Evolution Reaction

“…[51,52] The concave curvesf or Mo and Pi nt he energy dispersive spectroscopy line-scanp rofile also confirm the hollow structure ( Figure S4 in the Supporting Information), which has been demonstrated to be ad esired architecture for the efficient HER. [53][54][55][56] As shown in Figure4d, two sets of lattice fringes with d-spacings of about 0.21 and 0.28 nm refer to the (1 01)a nd (1 00)p lanes of the MoP phase, in good accordance with the XRD results. More interestingly,t he hollow nanospheres are composed of numerous randomly but tightly intertwined MoP subunits, along with some shrunken ones displaying this feature ( Figure S5 in the Supporting Information).…”

Retracted: Earth‐Abundant Iron Diboride (FeB2) Nanoparticles as Highly Active Bifunctional Electrocatalysts for Overall Water Splitting

“…The Tafel slope of 52.7 mV dec −1 for benchmark Pt/C is consistent with the value reported in the literature . FeB 2 exhibits a Tafel plot of a slope of 87.5 mV dec −1 , larger than that of Pt/C, but comparable or superior to that of many earth‐abundant HER catalysts reported recently, such as Co 2 B‐500/NG (92.4 mV dec −1 ), Ni–B x (88 mV dec −1 ), Cu 3 P‐550 (105 mV dec −1 ), h‐NiS x (99 mV dec −1 ), and MoO x /Ni 3 S 2 /NF (90 mV dec −1 ) . Generally, the HER pathway in alkaline electrolyte follows the Volmer–Heyrovsky or Volmer–Tafel mechanisms shown in Equations and …”

Nanosheet Supported Single-Metal Atom Bifunctional Catalyst for Overall Water Splitting

“…The high HER performance illustrated here and the excellent OER activity proposed above indicate that the Ni 1 /β 12 -BM is a promising bifunctional catalyst for the overall water splitting. It is worth noting that most of recent produced bifuncational electrocatalysts for the overall water splitting are also Ni-based materials (nickel phosphides, nitrides, sulfides, and oxides), − ,,− in line with our results that Ni 1 /β 12 -BM is active for both HER and OER, whereas other β 12 -BM based SACs are not. We conclude that the Ni 1 /β 12 -BM is a promising bifunctional SAC.…”

Hierarchical MoP Hollow Nanospheres Anchored on a N,P,S‐Doped Porous Carbon Matrix as Efficient Electrocatalysts for the Hydrogen Evolution Reaction

“…[51,52] The concave curvesf or Mo and Pi nt he energy dispersive spectroscopy line-scanp rofile also confirm the hollow structure ( Figure S4 in the Supporting Information), which has been demonstrated to be ad esired architecture for the efficient HER. [53][54][55][56] As shown in Figure4d, two sets of lattice fringes with d-spacings of about 0.21 and 0.28 nm refer to the (1 01)a nd (1 00)p lanes of the MoP phase, in good accordance with the XRD results. More interestingly,t he hollow nanospheres are composed of numerous randomly but tightly intertwined MoP subunits, along with some shrunken ones displaying this feature ( Figure S5 in the Supporting Information).…”