Fig. 1.

Spectroscopic characterizations of the as-prepared BP-based samples. a The formation process of the Co-P/BP nanosheets: (1) phase transition processes, (2) supporting process via the reaction between the formed BP nanosheets and Co(NO₃)₂. The reaction was run in ethylenediamine, followed by heating at 140 °C for 12 h, respectively. b XRD patterns of the BP (red line) and Co-P/BP (navy line) samples. c Raman spectra of the pristine BP and Co-P/BP samples. The excitation wavelength is 633 nm. d, e XPS fine spectra of P 2p and Co 2p states in the samples. The C 1s (284.8 eV) is the charged correction benchmark