“…The C 1s spectrum (Figure b) consists of the following four signals: 284.1, 284.8, 286.2, and 289.5 eV, which are centered on the C–B, C–N, CC, and C–O bonds, respectively . The N 1s spectrum (Figure c) is divided into five parts: 397.6, 398.5, 399.6, 401.3, and 406.1 eV corresponding to N–B bond, pyrrole N, pyridine N, graphite N, and N–Mo bond, respectively . For the Mo 3d spectrum (Figure d), the two prominent peaks at 232.0 and 228.7 eV can be attributed to Mo 3d 3/2 and Mo 3d 5/2 of Mo 4+ , respectively.…”