Exploiting active and stable non‐precious metal electrocatalysts for alkaline hydrogen evolution reaction (HER) at large current density plays a key role in realizing large‐scale industrial hydrogen generation. Herein, a self‐supported microporous Ni(OH)x/Ni3S2 heterostructure electrocatalyst on nickel foam (Ni(OH)x/Ni3S2/NF) that possesses super‐hydrophilic property through an electrochemical process is rationally designed and fabricated. Benefiting from the super‐hydrophilic property, microporous feature, and self‐supported structure, the electrocatalyst exhibits an exceptional HER performance at large current density in 1.0 M KOH, only requiring low overpotential of 126, 193, and 238 mV to reach a current density of 100, 500, and 1000 mA cm−2, respectively, and displaying a long‐term durability up to 1000 h, which is among the state‐of‐the‐art non‐precious metal electrocatalysts. Combining hard X‐rays absorption spectroscopy and first‐principles calculation, it also reveals that the strong electronic coupling at the interface of the heterostructure facilitates the dissociation of H2O molecular, accelerating the HER kinetics in alkaline electrolyte. This work sheds a light on developing advanced non‐precious metal electrocatalysts for industrial hydrogen production by means of constructing a super‐hydrophilic microporous heterostructure.
To explore efficient bifunctional electrocatalysts is crucial for constructing water splitting systems. In this work, a bifunctional catalyst NiCo layered double hydroxide (LDH) with nickel vacancies nanosheets was fabricated by...
The coordination atoms of metal active site in transition metal N-doped carbon single atom electrocatalysts play a vital role in dominating the catalytic performance of oxygen reduction reaction (ORR) at the cathode of fuel cells or metal-air cells. In view of weak adsorption ability of Ni active site in NiN 4 À C catalysts to oxygen intermediate states, herein we introduce boron atoms with smaller electronegativity than N and C atoms to modulate the local coordination environment and electronic structures of Ni site. First-principles density functional calculations reveal that both B substitution for N atoms (NiN 2 B 2 À C) and B coordinating with N and C (NiN 4 B 8 À C) can effectively optimize the Gibbs free energy of oxygen intermediate states and hence improve the catalytic activity of the materials. In addition, we propose that the trend change in catalytic activity is mainly governed by the filling of antibonding orbitals between Ni-3d and O-2p states near the Fermi level.
It
is indispensable to explore earth-abundant and high-efficiency
transition-metal-oxide electrocatalysts toward the hydrogen evolution
reaction (HER). However, their catalytic performance is impeded by
the poor conductivity. Herein we rationally design and manufacture
sulfur-doped Fe2O3 nanosheet arrays grown on
iron foam (S-Fe2O3/IF) with enhanced HER performance
in alkaline media. The obtained catalyst exhibits a low overpotential
of 134 mV to achieve a current density of 10 mA cm–2 with a small Tafel slope of 76 mV dec–1 and shows
an excellent long-term durability with barely any degradation for
50 h. The density functional theory calculation and experimental results
demonstrate that the sulfur anion could optimize adsorption free energies
of hydrogen/water and improve the intrinsic activity of Fe2O3. This work not only develops a catalyst with highly
efficient performance but also provides design guidance to rationally
manufacture an earth-abundant-element electrocatalyst for large-scale
water splitting to hydrogen.
Designing effective and low-cost bifunctional electrocatalysts
for the alkaline hydrogen evolution reaction (HER) and oxygen evolution
reaction (OER) is essential to achieve green development of the hydrogen
economy. Herein, we have developed Mo-doped Ni3S2 nanosheet array catalysts with excellent electrochemical properties.
Only 85 mV (HER) and 230 mV (OER) overpotentials are required under
alkaline conditions at 10 mA cm–2 and remain undegraded
for 100 h. In addition, it only required 1.52 V at 10 mA cm–2 in an alkaline electrolyzer, and it remained unchanged for more
than 100 h in stability tests, outperforming most reported electrocatalysts.
Experiments and density functional theory (DFT) calculations confirmed
that the doping of Mo could expose more active sites of Ni3S2 and optimize the adsorption free energy of the intermediate,
which in turn improves its intrinsic activity. This work reveals the
key role of Mo in Ni3S2 electrocatalytic performance
enhancement at the atomic scale.
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