Developing highly active and low-cost heterogeneous catalysts toward overall electrochemical water splitting is extremely desirable but still a challenge. Herein, we report pyrite NiS nanosheets doped with vanadium heteroatoms as bifunctional electrode materials for both hydrogen- and oxygen-evolution reaction (HER and OER). Notably, the electronic structure reconfiguration of pyrite NiS is observed from typical semiconductive characteristics to metallic characteristics by engineering vanadium (V) displacement defect, which is confirmed by both experimental temperature-dependent resistivity and theoretical density functional theory calculations. Furthermore, elaborate X-ray absorption spectroscopy measurements reveal that electronic structure reconfiguration of NiS is rooted in electron transfer from doped V to Ni sites, consequently enabling Ni sites to gain more electrons. The metallic V-doped NiS nanosheets exhibit extraordinary electrocatalytic performance with overpotentials of about 290 mV for OER and about 110 mV for HER at 10 mA cm with long-term stability in 1 M KOH solutions, representing one of the best non-noble-metal bifunctional electrocatalysts to date. This work provides insights into electronic structure engineering from well-designed atomic defect metal sulfide.
Designing
advanced electrocatalysts for hydrogen evolution reaction
is of far-reaching significance. Active sites and conductivity play
vital roles in such a process. Herein, we demonstrate a heteronanostructure
for hydrogen evolution reaction, which consists of metallic 1T-MoS2 nanopatches grown on the surface of flexible single-walled
carbon nanotube (1T-MoS2/SWNT) films. The simulated deformation
charge density of the interface shows that 0.924 electron can be transferred
from SWNT to 1T-MoS2, which weakens the absorption energy
of H atom on electron-doped 1T-MoS2, resulting in superior
electrocatalytic performance. The electron doping effect via interface
engineering renders this heteronanostructure material outstanding
hydrogen evolution reaction (HER) activity with initial overpotential
as small as approximately 40 mV, a low Tafel slope of 36 mV/dec, 108
mV for 10 mA/cm2, and excellent stability. We propose that
such interface engineering could be widely used to develop new catalysts
for energy conversion application.
Atomic intercalation in two dimensional (2D) layered materials can engineer the electronic structure at the atomic scale, bringing out tunable physical and chemical properties which are quite distinct in comparison with pristine one. Among them, electron-doped engineering induced by intercalation is an efficient route to modulate electronic states in 2D layers. Herein, we demonstrate a semiconducting to the metallic phase transition in zirconium diselenide (ZrSe2) single crystal via controllable incorporation of copper (Cu) atoms. Combined with first-principles density functional theory (DFT) calculations, our angle resolved photoemission spectroscopy (ARPES) characterizations clearly revealed the emergence of conduction band dispersion at M/L point of Brillouin zone due to Cu-induced electron doping in ZrSe2 interlayers. Moreover, the field-effect transistor (FET) fabricated on ZrSe2 displayed a n-type semiconducting transport behavior, while the Cu-intercalated ZrSe2 posed linear Ids vs Vds curves with metallic charactershows n-type doping. The atomic intercalation approach has high potential for realizing transparent electron-doping systems for many specific 2D-based electronics.
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