Interfacial electronic structure at a metal–phthalocyanine/graphene interface:Copper–phthalocyanine versus iron–phthalocyanine

The energy level alignment of CuPc and FePc on single-layer graphene/Ni（111） （SLG/Ni） substrate was investigated by using ultraviolet and X-ray photoelectron spectroscopy （UPS and XPS）. The highest occupied molecular orbitals （HO- MOs） in a thick layer of CuPc and FePc lie at 1.04 eV and 0.90 eV, respectively, below the Fermi level of the SLG/Ni substrate. Weak adsorbate-substrate interaction leads to negligible interfacial dipole at the CuPc/SLG/Ni interface, while a large interracial dipole （0.20 eV） was observed in the case of FePc/SLG/Ni interface, due to strong adsorbate-substrate coupling. In addition, a new interfacial electronic feature was observed for the first time in the case of FePc on SLG/Ni substrate. This interfacial state can be attributed to a charge transfer from the SLG/Ni substrate to unoccupied orbitals of FePc.

Engineering the interface of porous CoMoO_(3)nanosheets with Co_(3)Mo nanoparticles for high-performance electrochemical overall water splitting

The design of high-performance electrocatalysts for alkaline water splitting is of significant importance for the development of a sustainable hydrogen economy.Herein,heterostructured Co_(3)Mo nanoparti-cles/porous CoMoO_(3)nanosheets(Co_(3)Mo/CoMoO_(3)NPSs)were constructed for alkaline water splitting by annealing CoMoO x nanosheets under controlled atmospheres.Thanks to its interfacial electronic structure and increased electrochemical active area,Co_(3)Mo/CoMoO_(3)NPSs exhibit impressive hydrogen evolution reaction(HER)activity with an overpotential of 334 mV at 1000 mA cm^(-2) and a Tafel slope of 46.4 mV per decade in 1.0 M KOH,which outperforms Pt/C catalyst(621 mV and 74.7 mV per decade).Density functional theory calculations illustrate the electron transfer from Co_(3)Mo to CoMoO_(3)at the interfaces,where electron accumulation on CoMoO_(3)favors the dissociation of H_(2)O molecule,and electron-deficient Co atoms in Co_(3)Mo have optimized H∗absorption energy for HER.The Co_(3)Mo/CoMoO_(3)NPSs also exhibit higher oxygen evolution reaction activity than the RuO_(2)catalyst.Moreover,the water electrolyzer us-ing Co_(3)Mo/CoMoO_(3)NPSs as both cathode and anode only requires 1.59 V to deliver a current density of 100 mA cm^(-2)in 1.0 M KOH,which outperforms benchmark Pt/C||RuO_(2)electrodes couple with 1.69 V to reach the same current density,providing great potential for large-scale applications.