Regulation of crystallinity and defects on CoNiRuOx nanocages for enhanced oxygen evolution reaction

•A series of open-structured amorphous/crystalline CoNiRuOx heterointerface nanocages are prepared by a simple method.•The suitable crystallinity and defects levels could be simultaneously precise regulated.•The optimized CoNiRuOx-2 PNCs exhibited the superior OER activity with an overpotential of 245 mV at 10 mA cm−2.