Quiñonero Javier, Pastor Francisco J, Orts José M, Gómez Roberto
ACS Appl Mater Interfaces. 2021 Mar 31;13(12):14150-14159. doi: 10.1021/acsami.0c21792. Epub 2021 Mar 17.
Among the different strategies that are being developed to solve the current energy challenge, harvesting energy directly from sunlight through a tandem photoelectrochemical cell (water splitting) is most attractive. Its implementation requires the development of stable and efficient photocathodes, NdFeO being a suitable candidate among ternary oxides. In this study, transparent NdFeO thin-film photocathodes have been successfully prepared by a citric acid-based sol-gel procedure, followed by thermal treatment in air at 640 °C. These electrodes show photocurrents for both the hydrogen evolution and oxygen reduction reactions. Doping with Mg and Zn has been observed to significantly enhance the photoelectrocatalytic performance of NdFeO toward oxygen reduction. Magnesium is slightly more efficient as a dopant than Zn, leading to a multiplication of the photocurrent by a factor of 4-5 for a doping level of 5 at % (with respect to iron atoms). This same trend is observed for hydrogen evolution. The beneficial effect of doping is primarily attributed to an increase in the density and a change in the nature of the majority charge carriers. DFT calculations help to rationalize the behavior of NdFeO by pointing to the importance of nanostructuring and doping. All in all, NdFeO has the potential to be used as a photocathode in photoelectrochemical applications, although efforts should be directed to limit surface recombination.
在为解决当前能源挑战而正在开发的各种不同策略中，通过串联光电化学电池（水分解）直接从阳光中收集能量是最具吸引力的。其实现需要开发稳定且高效的光阴极，钕铁氧化物（NdFeO）是三元氧化物中的合适候选材料。在本研究中，通过基于柠檬酸的溶胶 - 凝胶法成功制备了透明的钕铁氧化物薄膜光阴极，随后在空气中640℃进行热处理。这些电极对析氢反应和氧还原反应均显示出光电流。已观察到用镁（Mg）和锌（Zn）掺杂可显著提高钕铁氧化物对氧还原的光电催化性能。作为掺杂剂，镁比锌略有效，对于5原子百分比（相对于铁原子）的掺杂水平，光电流增加4 - 5倍。对于析氢反应也观察到相同趋势。掺杂的有益效果主要归因于多数电荷载流子密度的增加和性质的变化。密度泛函理论（DFT）计算通过指出纳米结构和掺杂的重要性，有助于解释钕铁氧化物的行为。总而言之，钕铁氧化物有潜力用作光电化学应用中的光阴极，尽管应致力于限制表面复合。
