The hydrothermal synthesis of the perovskites NaNbO₃, NaTaO₃ and the intermediate composition NaNb_0.5Ta_0.5O₃, as CO₂ conversion photocatalysts is reported. Among them, the niobate shows the most promising performance under UV irradiation not only in terms of conversion and light utilization ability, but also regarding the selectivity towards CO₂ reduction against hydrogen evolution from water protons. Further modification of NaNbO₃ with silver as co-catalyst results in an increase of the selectivity towards highly reduced products, primarily methanol, against the carbon monoxide production mainly observed with the bare semiconductor. A thorough structural, electronic, electrochemical characterization, together with in-situ surface analysis by APXPS, was undertaken to gain deeper insight into the reasons that account for such changes. On the one hand, for the bare semiconductors, increased light absorption and the sole presence of Nb in +4 state at the surface seem to drive the superior activity of NaNbO₃. On the other hand, electronic and surface chemistry modifications induced by 0.1 wt.% silver deposition are proposed to govern the higher selectivity towards methanol. Excessive metal loading, in turn, enhances the selectivity effect but at the expense of conversion, in such a way that light utilization becomes poorer than with the bare niobate.

报道了水热合成钙钛矿NaNbO ₃，NaTaO ₃和中间组成NaNb _0.5 Ta _0.5 O ₃，作为CO ₂转化光催化剂。其中，铌酸盐不仅在转化率和光利用能力方面，而且在针对从水质子中析出的氢对CO ₂还原的选择性方面，在紫外线照射下均显示出最有前途的性能。NaNbO _3的进一步改性用银作为助催化剂可提高对高度还原的产物（主要是甲醇）的选择性，而选择性主要针对裸半导体中一氧化碳的产生。进行了彻底的结构，电子，电化学表征以及APXPS进行的原位表面分析，以更深入地了解造成这种变化的原因。一方面，对于裸露的半导体，增加的光吸收和表面上+4状态的Nb的唯一存在似乎驱动了NaNbO ₃的优异活性。。另一方面，提出了由0.1重量％的银沉积引起的电子和表面化学修饰，以控制对甲醇的更高选择性。反过来，过量的金属负载会增强选择性效果，但会以转化为代价，从而使光利用率变得比裸铌酸盐差。