Molybdenum dichalcogenide nanotube arrays for hydrogen-evolution-reaction catalysis: Synergistic effects of sulfur and selenium in a core-shell tube wall

•Growth of self-organized anodic molybdenum oxide nanotube arrays•Fabrication of a core-shell structure consisting of a Mo sub-oxide core and a shell of Mo-Se/S•Synergistic effect of the mixed dichalcogenide and the conductive core for enhanced HER activity

The present work shows the growth and conversion of self-organized anodic Mo-oxide nanotube arrays to core-shell structures consisting of a conducting molybdenum sub-oxide core and a shell of Mo-Se/S - this structure is then investigated for electrochemical hydrogen evolution catalysis. To form the core-shell tubes, we first anneal MoO3 nanotube arrays under vacuum conditions, to induce reduction to MoO2. Subsequently these oxide tubes are thermally sulfurized and selenized resulting in dichalcogenide@sub-oxide structures. Under optimized conditions, the mixed dichalcogenide (selenized and sulfurized) tube walls on the conductive oxide core lead to a synergistic beneficial effect for the electrocatalytic H2 generation from H2SO4 solution.