Sodium-ion batteries (SIBs) are considered as a promising alternative to lithium-ion batteries, due to the abundant reserves and low price of Na sources. To date, the development of anode materials for SIBs is still confronted with many serious problems. In this work, encapsulation-type structured MoSe 2 @hollow carbon nanosphere (HCNS) materials assembled with expanded (002) planes few-layer MoSe 2 nanosheets confined in HCNS are successfully synthesized through a facile strategy. Notably, the interlayer spacing of the (002) planes is expanded to 1.02 nm, which is larger than the intrinsic value of pristine MoSe 2 (0.64 nm). Furthermore, the few-layer nanosheets are space-confined in the inner cavity of the HCNS, forming hybrid MoSe 2 @HCNS structures. When evaluated as anode materials for SIBs, it shows excellent rate capabilities, ultralong cycling life with exceptional Coulombic efficiency even at high current density, maintaining 501 and 471 mA h g −1 over 1000 cycles at 1 and 3 A g −1 , respectively. Even when cycled at current densities as high as 10 A g −1 , a capacity retention of 382 mA h g −1 can be achieved. The expanded (002) planes, 2D few-layer nanosheets, and unique carbon shell structure are responsible for the ultralong cycling and high rate performance.

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The poor catalyst stability in acidic oxidation evolution reaction (OER) has been a long-time issue. Herein, we introduce electron-deficient metal on semiconducting metal oxides-consisting of Ir (Rh, Au, Ru)-MoO3 embedded by graphitic carbon layers (IMO) using an electrospinning method. We systematically investigate IMO’s structure, electron transfer behaviors, and OER catalytic performance by combining experimental and theoretical studies. Remarkably, IMO with an electron-deficient metal surface (Irx+; x > 4) exhibit a low overpotential of only ~156 mV at 10 mA cm−2 and excellent durability in acidic media due to the high oxidation state of metal on MoO3. Furthermore, the proton dissociation pathway is suggested via surface oxygen serving as proton acceptors. This study suggests high stability with high catalytic performance in these materials by creating electron-deficient surfaces and provides a general, unique strategy for guiding the design of other metal-semiconductor nanocatalysts.

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