Attarzadeh Navid, Das Debabrata, Chintalapalle Srija N, Tan Susheng, Shutthanandan V, Ramana C V
Centre for Advanced Materials Research (CMR), University of Texas at El Paso, 500 W. University Ave., El Paso, Texas 79968, United States.
Environmental Science and Engineering, University of Texas at El Paso, 500 W. University Ave., El Paso, Texas 79968, United States.
ACS Appl Mater Interfaces. 2023 May 10;15(18):22036-22050. doi: 10.1021/acsami.3c00781. Epub 2023 Apr 26.
The projection of developing sustainable and cost-efficient electrocatalysts for hydrogen production is booming. However, the full potential of electrocatalysts fabricated from earth-abundant metals has yet to be exploited to replace Pt-group metals due to inadequate efficiency and insufficient design strategies to meet the ever-increasing demands for renewable energies. To improve the electrocatalytic performance, the primary challenge is to optimize the structure and electronic properties by enhancing the intrinsic catalytic activity and expanding the active catalytic surface area. Herein, we report synthesizing a 3D nanoarchitecture of aligned NiP-NiP/NiS (plate/nanosheets) using a phospho-sulfidation process. The durability and unique design of prickly pear cactus in desert environments by adsorbing moisture through its extensive surface and ability to bear fruits at the edges of leaves inspire this study to adopt a similar 3D architecture and utilize it to design an efficient heterostructure catalyst for HER activity. The catalyst comprises two compartments of the vertically aligned NiP-NiP plates and the NiS nanosheets, resembling the role of leaves and fruits in the prickly pear cactus. The NiP-NiP plates deliver charges to the interface areas, and the NiS nanosheets significantly influence H and transfer electrons for the HER activity. Indeed, the synergistic presence of heterointerfaces and the epitaxial NiS nanosheets can substantially improve the catalytic activity compared to nickel phosphide catalysts. Notably, the onset overpotential of the best-modified ternary catalysts exhibits (35 mV) half the potential required for nickel phosphide catalysts. This promising catalyst demonstrates 70 and 115 mV overpotentials to attain current densities of 10 and 100 mA cm, respectively. The obtained Tafel slope is 50 mV dec, and the measured double-layer capacitance from cyclic voltammetry (CV) for the best ternary electrocatalyst is 13.12 mF cm, 3 times more than the nickel phosphide electrocatalyst. Further, electrochemical impedance spectroscopy (EIS) at the cathodic potentials reveals that the lowest charge transfer resistance is linked to the best ternary electrocatalyst, ranging from 430 to 1.75 Ω cm. This improvement can be attributed to the acceleration of the electron exchangeability at the interfaces. Our findings demonstrate that the epitaxial NiS nanosheets expand the active catalytic surface area and simultaneously elevate the intrinsic catalytic activity by introducing heterointerfaces, which leads to accommodating more H at the interfaces.
开发可持续且具有成本效益的析氢电催化剂的前景一片光明。然而，由于效率不足以及缺乏足够的设计策略来满足对可再生能源不断增长的需求，由储量丰富的金属制成的电催化剂的全部潜力尚未得到充分利用以取代铂族金属。为了提高电催化性能，主要挑战是通过增强本征催化活性和扩大活性催化表面积来优化结构和电子性能。在此，我们报告了通过磷硫化过程合成一种对齐的NiP-NiP/NiS（板/纳米片）三维纳米结构。沙漠环境中仙人掌通过其广泛的表面吸附水分以及在叶缘结果实的耐久性和独特设计启发了本研究采用类似的三维结构并利用它来设计一种用于析氢活性的高效异质结构催化剂。该催化剂由垂直对齐的NiP-NiP板和NiS纳米片两个部分组成，类似于仙人掌中叶和果实的作用。NiP-NiP板将电荷传递到界面区域，而NiS纳米片对析氢活性中的氢和转移电子有显著影响。实际上，与磷化镍催化剂相比，异质界面和外延NiS纳米片的协同存在可显著提高催化活性。值得注意的是，最佳改性三元催化剂的起始过电位为35 mV，是磷化镍催化剂所需电位的一半。这种有前景的催化剂在达到10和100 mA cm的电流密度时分别表现出70和115 mV的过电位。获得的塔菲尔斜率为50 mV dec，最佳三元电催化剂通过循环伏安法（CV）测量的双层电容为13.12 mF cm，是磷化镍电催化剂的3倍。此外，阴极电位下的电化学阻抗谱（EIS）表明，最低的电荷转移电阻与最佳三元电催化剂相关，范围为430至1.75 Ω cm。这种改善可归因于界面处电子交换能力的加速。我们的研究结果表明，外延NiS纳米片通过引入异质界面扩大了活性催化表面积，同时提高了本征催化活性，这导致在界面处容纳更多的氢。
