. 2025 Sep 26;7(22):7156–7170. doi: 10.1039/d5na00664c

Table 2. The composition of Cu₄O₃-x films determined by XPS spectra.

Samples	Cu₄O₃-0	Cu₄O₃-10	Cu₄O₃-20	Cu₄O₃-30	Cu₄O₃-40
% at. Cu²⁺	28.03	28.68	28.99	29.18	29.19
% at. Cu¹⁺	31.42	29.56	28.56	27.7	26.96
% at. Cu(Cu¹⁺ + Cu²⁺)	59.45	58.24	57.55	56.88	56.15
% at. O_Cu2	23.76	24.45	24.84	25.15	24.59
% at. O_Cu1	13.37	12.79	12.76	12.61	12.35
% at. V_O	2.96	2.11	1.81	1.21	0.9
% at. O(O₁ + O₂ + V_O)	40.09	39.35	39.41	38.97	37.84
% at. N	0.46	2.41	3.04	4.15	6.01
	≈0.89	≈0.97	≈1.02	≈1.05	≈1.08
	≈1.78	≈1.91	≈1.95	≈1.99	≈1.99
	≈1.47	≈1.40	≈1.36	≈1.32	≈1.28

Table 2. The composition of Cu4O3-x films determined by XPS spectra.