Home > News > Advanced energy materials: electronic structure control of ultrathin nitrogen rich co-mo5n6 heterojunction to enhance electrocatalytic hydrogen evolution performance

Advanced energy materials: electronic structure control of ultrathin nitrogen rich co-mo5n6 heterojunction to enhance electrocatalytic hydrogen evolution performance

wallpapers News 2020-12-05
Because of its high calorific value environmental friendliness

is regarded as an ideal energy in the future. So far the large-scale hydrogen production mainly depends on the consumption of fossil fuels which causes serious pollution. However the current large-scale hydrogen production from water electrolysis is limited by the use of precious metal catalysts to reduce the reaction energy barrier the stability is poor under the high current density required by commercialization so the technology has not been widely popularized. The development of transition metal catalysts for water electrolysis has become a hot spot.

transition metal nitrides are considered as one of the effective substitutes because of their similar electronic states to noble metals. In particular transition metal nitrogen rich phase nitrides have the advantages of high activity long-term stability. The high temperature high pressure reaction conditions of conventional synthesis are one of the obstacles to its extensive research. At the same time due to the thermodynamic instability it is challenging to synthesize ultra-thin two-dimensional nanosheets to improve the mass transfer rate conductivity further adjust nitrogen rich nitrides with excellent electronic structure to improve their hydrogen production activity so as to meet the requirements of commercial current density.

recently Jiao Lifang research group of Nankai University prepared metal co nitrogen rich nitride (co-mo5n6) ultra thin heterojunction materials by simple ammonia atmosphere calcination process. The formation of co-mo5n6 ultrathin heterojunction stabilizes the nitrogen rich nitrides realizes the electron transfer between the two phases. At the same time co-mo5n6 heterojunction materials are connected by ultra-thin nanosheets (≈ 1.2nm) construction units which cause open connected channels improve the specific surface area conductivity the strong capillary force will also accelerate the mass transfer. The experimental results show that co-mo5n6 has excellent her activity the overpotential is only 19 MV at a current density of 10 Ma cm-2. In addition only 280 MV overpotential is needed to achieve 1000 Ma cm-2 ultra-high current density which is better than commercial Pt / C. This work not only improves the understing of catalytic activity electron redistribution of nitrogen rich nitrides but also proposes new strategies for designing other nitrogen rich metal nitrides (such as w2n3 ta5n6). The

XPS spectra DFT simulations verify the electron transfer between the ultra-thin heterostructures. Density functional theory (DFT) simulation shows that the electron distribution between the nitrogen rich phase CO in the obtained co-mo5n6 material results in a more negative H2O adsorption energy (- 0.79 EV) a lower H2O dissociation barrier (0.05 EV) the adsorption of h * is optimized (Δ GH * = 0.1 EV).

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