Chaudhary Sonu Pratap, Bhattacharjee Subhajit, Hazra Vishwadeepa, Shyamal Sanjib, Pradhan Narayan, Bhattacharyya Sayan
Department of Chemical Sciences and Centre for Advanced Functional Materials, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur 741246, India.
School of Materials Sciences, Indian Association for the Cultivation of Science, Kolkata 700032, India.
Nanoscale. 2022 Mar 17;14(11):4281-4291. doi: 10.1039/d1nr07008h.
The increasingly popular, lead-free perovskite, CsBiI has a vulnerable Bi state under reductive potentials, due to the high standard reduction potential of Bi/Bi (0 < < 3). Contrary to this fundamental understanding, herein, ligand-coated CsBiI nanodiscs (NDs) demonstrate outstanding electrochemical stability with up to -1 V a saturated calomel electrode in aqueous 0.63 M (5% v/v) and 6.34 M (50% v/v) hydroiodic acid (HI), with a minor BiI fraction due to the unavoidable partial aqueous disintegration of the perovskite phase after 8 and 16 h, respectively. A dynamic equilibrium of saturated 0.005 M NDs maintains the common ion effect of I, and remarkably stabilizes ∼93% Bi in 0.63 M HI under a strong reductive potential. In comparison, the hexagonal phase of bulk CsBiI disintegrates considerably in the semi-aqueous media. Lowering the concentration of synthetic HI from the commonly used ∼50% v/v by elevating the pH from -0.8 to 0.2 helps in reducing the cost per unit of H production. Our CsBiI NDs with a hexagonal lattice have 4-6 (002) planes stacked along the -axis. With 0.005 M photostable NDs, 22.5 μmol h H is photochemically obtained within 8 h in a 6.34 M HI solution. Electrocatalytic H evolution occurs with a turnover frequency of 11.7 H per s at -533 mV and outstanding operational stability for more than 20 h.
日益流行的无铅钙钛矿CsBiI在还原电位下Bi状态不稳定，这是由于Bi/Bi的标准还原电位较高（0 << 3）。与这种基本认识相反，在此，配体包覆的CsBiI纳米盘（NDs）在0.63 M（5% v/v）和6.34 M（50% v/v）氢碘酸（HI）水溶液中相对于饱和甘汞电极具有高达-1 V的出色电化学稳定性，由于钙钛矿相不可避免地分别在8小时和16小时后发生部分水相分解，BiI的比例较小。饱和的0.005 M NDs的动态平衡维持了I的共同离子效应，并在强还原电位下在0.63 M HI中显著稳定了约93%的Bi。相比之下，块状CsBiI的六方相在半水介质中会大量分解。通过将pH从-0.8提高到0.2来降低常用的约50% v/v的合成HI浓度，有助于降低每单位H生产的成本。我们具有六方晶格的CsBiI NDs沿轴堆叠有4 - 6个（002）平面。使用0.005 M光稳定的NDs，在6.34 M HI溶液中8小时内光化学获得22.5 μmol h H。在-533 mV下发生电催化析氢，周转频率为每秒11.7个H，并且具有超过20小时的出色操作稳定性。
