ABSTRACT
Exploring and developing novel strategies for constructing heterostructure electrocatalysts is still challenging for water electrolysis. Herein, a creative etching treatment strategy is adopted to construct NiSe2 /Ni0.85 Se heterostructure. The rich heterointerfaces between NiSe2 and Ni0.85 Se emerge strong electronic interaction, which easily induces the electron transfer from NiSe2 to Ni0.85 Se, and tunes the charge-state of NiSe2 and Ni0.85 Se. In the NiSe2 /Ni0.85 Se heterojunction nanomaterial, the higher charge-state Ni0.85 Se is capable of affording partial electrons to combine with hydrogen protons, inducing the rapid formation of H2 molecule. Accordingly, the lower charge-state NiSe2 in the NiSe2 /Ni0.85 Se heterojunction nanomaterial is more easily oxidized into high valence state Ni3+ during the oxygen evolution reaction (OER) process, which is beneficial to accelerate the mass/charge transfer and enhance the electrocatalytic activities towards OER. Theoretical calculations indicate that the heterointerfaces are conducive to modulating the electronic structure and optimizing the adsorption energy toward intermediate H* during the hydrogen evolution reaction (HER) process, leading to superior electrocatalytic activities. To expand the application of the NiSe2 /Ni0.85 Se-2h electrocatalyst, urea is served as the adjuvant to proceed with the energy-saving hydrogen production and pollutant degradation, and it is proven to be a brilliant strategy.
ABSTRACT
Modulation of the electronic interaction between the metal and support has been verified as a feasible strategy to improve the electrocatalytic performance of supported-type catalysts. Here, we have successfully synthesized an electrocatalyst of Ni2P nanoparticles (NPs) anchored on B, N co-doped graphite-like carbon nanosheets (Ni2P@B, N-GC), and elucidated the main mechanism by which B atoms doping enhances electrocatalytic hydrogen evolution reaction (HER) performance. The B atoms with electron-rich characteristic not only modulate the electronic structure on carbon skeleton, but also regulate the interfacial electronic interaction between Ni2P NPs and the carbon skeleton, which can lead to the increased available electron density of Ni sites. Such optimization is conducive to accelerating proton transfer and promoting reactive activity. As revealed, the Ni2P@B, N-GC catalyst with B atoms doping exhibits superior performance to the Ni2P@N-GC catalyst in acidic, neutral and alkaline medias. In addition, the assembled Ni(OH)2@B, N-GC||Ni2P@B, N-GC electrolyzer displays prominent overall water splitting performance in alkaline solution, which only demands 1.57 V to reach 10 mA/cm2, and in complicated natural seawater electrolyte, as low as 1.59 V. Hence, the B atoms doping strategy shows the significant enhancement for HER electrocatalysis.
ABSTRACT
Heteroatoms Fe, F co-doped NiO hollow spheres (Fe, F-NiO) are designed, which simultaneously integrate promoted thermodynamics by electronic structure modulation with boosted reaction kinetics by nano-architectonics. Benefiting from the electronic structure co-regulation of Ni sites by introducing Fe and F atoms in NiO , as the rate-determined step (RDS), the Gibbs free energy of OH* intermediates (ΔGOH* ) for Fe, F-NiO catalyst is significantly decreased to 1.87 eV for oxygen evolution reaction (OER) compared with pristine NiO (2.23 eV), which reduces the energy barrier and improves the reaction activity. Besides, densities of states (DOS) result verifies the bandgap of Fe, F-NiO(100) is significantly decreased compared with pristine NiO(100), which is beneficial to promote electrons transfer efficiency in electrochemical system. Profiting by the synergistic effect, the Fe, F-NiO hollow spheres only require the overpotential of 215 mV for OER at 10 mA cm-2 and extraordinary durability under alkaline condition. The assembled Fe, F-NiO||Fe-Ni2 P system only needs 1.51 V to reach 10 mA cm-2 , also exhibits outstanding electrocatalytic durability for continuous operation. More importantly, replacing the sluggish OER by advanced sulfion oxidation reaction (SOR) not only can realize the energy saving H2 production and toxic substances degradation, but also bring additional economic benefits.
