Abstract In this contribution, we present an experimental and theoretical investigation of the role of counter-ions in the crystal morphology, surface structure, and photocatalytic activity of hierarchical ZnO nanostructures. The effect of zinc precursor (nitrate, acetate and, sulfate) along the synthesis of ZnO nanostructures grown directly onto a substrate by means of a simple hydrothermal method was analyzed in detail. Scanning electron microscopy images showed a preferential growth of ZnO nanostructures along the c-axis, with a slight reduction in the orientation depending on the choice of the Zn source. Theoretical calculations based on the Wulff theory allowed us to better understand the morphological changes and directly relate the photocatalytic performance at the different exposed surfaces of the as-observed crystal shapes. Our results showed that photocatalytic activities in the discoloration of organic dyes became superior for hierarchical ZnO nanostructures obtained from zinc nitrate. This finding was explained by X-ray photoelectron and photoluminescence spectroscopies, which revealed that in addition to, the attached counter-ions and the abundance of carboxylate groups and organic residuals on ZnO surfaces, the presence of surface defects are determinant to enhance the photocatalytic performance of the material.

中文翻译：

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反离子在基板上生长的 ZnO 晶体的晶体形态、表面结构和光催化活性中的作用

摘要 在这篇文章中，我们对反离子在分级 ZnO 纳米结构的晶体形态、表面结构和光催化活性中的作用进行了实验和理论研究。详细分析了锌前体（硝酸盐、醋酸盐和硫酸盐）对通过简单的水热法直接生长在基板上的 ZnO 纳米结构的合成的影响。扫描电子显微镜图像显示 ZnO 纳米结构沿 c 轴优先生长，根据 Zn 源的选择，取向略有减少。基于伍尔夫理论的理论计算使我们能够更好地理解形态变化，并直接关联观察到的晶体形状不同暴露表面的光催化性能。我们的结果表明，从硝酸锌获得的分级 ZnO 纳米结构在有机染料变色方面的光催化活性变得更好。这一发现可以通过 X 射线光电子和光致发光光谱来解释，这表明除了附着的反离子和丰富的羧酸根基团和 ZnO 表面的有机残留物外，表面缺陷的存在也是提高光催化性能的决定因素的材料。