The solid solution photocatalyst plays a vital role in designing the one-step excitation water splitting system. However, the co-existence of the evolution of surface heterostructure together with the gradual formation of solid solutions makes it difficult to distinguish the inherent role of solid solution and surface structure in OWS reaction. Herein, Bi 0.5 Y 0.5 VO 4 solid solution was synthesized through a fine-tuned co-precipitation procedure at room temperature, which acted as starting materials for further annealing treatment. Systematic characterizations revealed that variations in surface B-V-O domain at different temperatures induced the generation of particular heterogeneous structures in the solid solution surface. After annealing at 600 °C, the surface V-rich amorphous layer on Bi 0.5 Y 0.5 VO 4 delivered functional electron trapping and optimized reaction dynamics, leading to enhanced OWS activity. In contrast, a nano-junction alignment formed at 800 °C near the surface resulted in an inappropriate band structure and poor charge dynamics, finally suppressing the OWS activity.
Nickel-rich (Ni ≥ 90%) layered oxides materials have emerged as a promising candidate for next-generation high-energy-density lithium-ion batteries (LIBs). However, their widespread application is hindered by structural fatigue and lattice oxygen loss. In this work, an epitaxial surface rock-salt nanolayer is successfully developed on the LiNi 0.9 Co 0.1 O 2 sub-surface via heteroatom anchoring utilizing high-valence element molybdenum modification. This in-situ formed conformal buffer phase with a thickness of 1.2 nm effectively suppresses the continuous interphase side-reactions, and thus maintains the excellent structure integrity at high voltage. Furthermore, theoretical calculations indicate that the lattice oxygen reversibility in the anion framework of the optimized sample is obviously enhanced due to the higher content of O 2 p states near the Fermi level than that of the pristine one. Meanwhile, the stronger Mo–O bond further reduces cell volume alteration, which improves the bulk structure stability of modified materials. Besides, the detailed charge compensation mechanism suggests that the average oxidation state of Ni is reduced, which induces more active Li + participating in the redox reactions, boosting the cell energy density. As a result, the uniquely designed cathode materials exhibit an extraordinary discharge capacity of 245.4 mAh g −1 at 0.1 C, remarkable rate performance of 169.3 mAh g −1 at 10 C at 4.5 V, and a high capacity retention of 70.5% after 1000 cycles in full cells at a high cut-off voltage of 4.4 V. This strategy provides an valuable insight into constructing distinctive heterostructure on high-performance Ni-rich layered cathodes for LIBs.
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