A uniformly distributed bismuth nanoparticle-modified carbon cloth electrode for vanadium redox flow batteries

•A bottom-to-up strategy is adopted to design, fabricate and test the electrode.•Increasing O-functional groups enhances the numbers and activity of active sites.•All the experimental results are consistent with the computational predictions.•The battery delivers an EE of 80.1% and EU of 69.8% at 320 mA cm−2.•The high-performance is related to the good transport properties of carbon cloth.