In situ grown Co3O4 on hydrogen storage alloys for enhanced electrochemical performance

•Co3O4 nanosheets in situ growing on hydrogen storage alloys were prepared.•The fabrication strategy of the composites is simple, facile and effective.•Hybrid electrodes show enhanced discharge capacity and high-rate dischargeability.•The mechanisms behind enhanced electrochemical performance are revealed.

Co3O4 is an effective additive to enhance the electrochemical performance of hydrogen storage alloys. However, the low utilization efficiency has become a big challenge for direct adding Co3O4 powders into the alloys with mechanical mixing. Here, we report the in situ growth of Co3O4 on the alloy surface by using a facile and effective hydrothermal method. Compared with bare hydrogen storage alloys, the fabricated composite shows larger maximum discharge capacity, 326.37 vs. 302.62 mAh g−1, and enhanced high rate dischargeability with larger discharge capacity at a current density of 3000 mA g−1, 59.01 vs. 40.88 mAh g−1. These are contributed by the unique hybrid architecture of the composite: (1) the in situ grown Co3O4 nanosheets improve the catalytic activity and utilization efficiency of Co3O4 on the electrochemical reaction kinetics; and (2) the low-dimensional Co3O4 coatings seamlessly integrated with hydrogen storage alloys decrease the internal resistance and polarization of the hybrid electrode. Such a simple and novel method can also be extended to other energy storage devices.