RESUMO
An n-n type heterojunction comprising with CuN and BN dual active sites is synthesized via in situ growth of a conductive metal-organic framework (MOF) [Cu3 (HITP)2 ] (HITP = 2,3,6,7,10,11-hexaiminotriphenylene) on hexagonal boron nitride (h-BN) nanosheets (hereafter denoted as Cu3 (HITP)2 @h-BN) for the electrocatalytic nitrogen reduction reaction (eNRR). The optimized Cu3 (HITP)2 @h-BN shows the outstanding eNRR performance with the NH3 production of 146.2 µg h-1 mgcat -1 and the Faraday efficiency of 42.5% due to high porosity, abundant oxygen vacancies, and CuN/BN dual active sites. The construction of the n-n heterojunction efficiently modulates the state density of active metal sites toward the Fermi level, facilitating the charge transfer at the interface between the catalyst and reactant intermediates. Additionally, the pathway of NH3 production catalyzed by the Cu3 (HITP)2 @h-BN heterojunction is illustrated by in situ FT-IR spectroscopy and density functional theory calculation. This work presents an alternative approach to design advanced electrocatalysts based on conductive MOFs.
RESUMO
A defect-rich 2D p-n heterojunction, Cox Ni3- x (HITP)2 /BNSs-P (HITP: 2,3,6,7,10,11-hexaiminotriphenylene), is constructed using a semiconductive metal-organic framework (MOF) and boron nanosheets (BNSs) by in situ solution plasma modification. The heterojunction is an effective catalyst for the electrocatalytic nitrogen reduction reaction (eNRR) under ambient conditions. Interface engineering and plasma-assisted defects on the p-n Cox Ni3-x (HITP)2 /BNSs-P heterojunction led to the formation of both Co-N3 and B O dual-active sites. As a result, Cox Ni3-x (HITP)2 /BNSs-P has a high NH3 yield of 128.26 ± 2.27 µg h-1 mgcat. -1 and a Faradaic efficiency of 52.92 ± 1.83% in 0.1 m HCl solution. The catalytic mechanism for the eNRR is also studied by in situ FTIR spectra and DFT calculations. A Cox Ni3- x (HITP)2 /BNSs-P-based Zn-N2 battery achieved an unprecedented power output with a peak power density of 5.40 mW cm-2 and an energy density of 240 mA h gzn -1 in 0.1 m HCl. This study establishes an efficient strategy for the rational design, using defect and interfacial engineering, of advanced eNRR catalysts for ammonia synthesis under ambient conditions.
RESUMO
In this work, a two-dimensional heterostructure of molybdenum disulfide (MoS2) and nickelhydroxyloxide (NiOOH) nanosheets supported on catkin-derived mesoporous carbon (C-MC) was constructed and exploited as an efficient electrocatalyst for overall water splitting. The C-MC nanostructure was prepared by pyrolyzing biomass material of catkin at 600 °C in N2 atmosphere. The C-MC network exhibited hollow nanotube structure and had a large specific surface area, comprising trace nitrogen and a large amount of oxygen vacancies. It further served as the support for the growth of NiOOH nanosheets (NiOOH@C-MC), which was combined with MoS2 nanosheets by in situ growth, yielding a multicomponent electrocatalyst (MoS2@NiOOH@C-MC). By integrating the superior hydrogen evolution reaction (HER) performance of MoS2, oxygen evolution reaction (OER) performance of NiOOH, and the fast electron transfer capability of C-MC, the prepared MoS2@NiOOH@C-MC illustrated a low potential of - 250 mV for HER and 1.51 V for OER at the current density of 10 mV cm-2. Consequently, when applied as the working electrode for driving overall water splitting in a two-electrode system, the bifunctional MoS2@NiOOH@C-MC electrocatalyst displayed a low cell voltage of 1.62 V at the current density of 10 mA cm-2. The present work provides a new strategy that uses biomass material for developing bifunctional electrocatalyst for overall water splitting.
