本研究调查了本征应变和相变对Cu1-xAxAlO2固溶体的热力学稳定性和电子性质的影响,这是它们光催化性能的关键。证明了A=Ag的Cu1-xAxAlO2,Au,由于相对较小的压缩应变,Pt可以形成连续的等结构固溶体,而大幅增加的应变限制了Cu1-xPdxAlO2仅形成有限的溶液。对于A=Li,Na,结构基序改变促进了异质结构固溶体的形成,适应离子半径和A-O键特性的显着差异。具体来说,Cu1-xLixAlO2在x≈0.333处表现出相变,而Cu1-xNaxAlO2经历了三个不同的相变。电子结构分析表明,在Cu1-xAxAlO2(A=Ag,Au),d10-d10闭壳相互作用占主导地位,实现具有不同溶解度的可调带隙。然而,金属亚晶格中固有应变增加,如A=Pd和Pt所示,将反键状态转移到费米能级,诱导半导体到金属的过渡。实验证据证实,Ag离子可调节Cu1-xAgxAlO2中的带隙和载流子动力学,其中Cu0.75Ag0.25AlO2表现出更高的光电化学活性,H2生产率比CuAlO2提高了38.5倍。此外,碱金属和O之间的协调环境变化,由相变诱导,有效地调谐Cu1-xAxAlO2的带边缘位置和载流子动力学(A=Li,Na)异质结构固溶体。因此,具有非对称非线性哑铃O-Cu-O的3R-Cu0.97Li0.03AlO2表现出最高的光催化H2生产活性,比CuAlO2大72.9倍。相比之下,具有较小的CuO6八面体分裂能的α-Cu1-xAxAlO2表现出增加的带隙,导致光催化活性下降。这项研究强调了应变驱动的相变为调节Cu1-xAxAlO2固溶体的光(电)催化活性提供了额外的控制因素和新机制。
This study investigates the impact of intrinsic strain and phase transitions on the thermodynamic stability and electronic properties of Cu1-xAxAlO2 solid solutions, which are key to their photocatalytic performance. It is demonstrated that Cu1-xAxAlO2 with A = Ag, Au, Pt can form continuous isostructural solid solutions due to relatively small compressive strain, while a substantial increase strain restricts Cu1-xPdxAlO2 to forming only limited solutions. For A = Li, Na, the formation of heterostructural solid solutions is facilitated by structural motif alterations, accommodating significant differences in ionic radii and A-O bond characteristics. Specifically, Cu1-xLixAlO2 exhibits a phase transition at x ≈ 0.333, whereas Cu1-xNaxAlO2 undergoes three distinct phase transitions. Electronic structure analysis indicates that in Cu1-xAxAlO2 (A = Ag, Au), d10-d10 closed-shell interactions dominate, enabling tunable band gaps with varying solubility. Nevertheless, increased intrinsic strain in metal sublattices, as seen in A = Pd and Pt, shifts antibonding states to the Fermi level, inducing a semiconductor-to-metal transition. Experimental evidence confirms that Ag+ ions modulate the band gaps and carrier dynamics in Cu1-xAgxAlO2, with Cu0.75Ag0.25AlO2 exhibiting heightened photoelectrochemical activity and a 38.5-fold enhancement in H2 production rate over CuAlO2. Additionally, the coordination environment changes between alkali metals and O, induced by phase transitions, effectively tune the band edge positions and carrier dynamics of Cu1-xAxAlO2 (A = Li, Na) heterostructural solid solutions. Therefore, 3R-Cu0.97Li0.03AlO2 with asymmetric nonlinear dumbbell O-Cu-O demonstrates the highest photocatalytic H2 production activity, 72.9 times greater than CuAlO2. In contrast, α-Cu1-xAxAlO2 with a smaller CuO6 octahedral splitting energy exhibits increased band gaps, resulting in diminished photocatalytic activity. This research underscores that strain-driven phase transition provides an additional control factor and new mechanism for regulating the photo(electro)catalytic activity of Cu1-xAxAlO2 solid solutions.