Modulating p-Orbital of Bismuth Nanosheet by Nickel Doping for Electrocatalytic Carbon Dioxide Reduction Reaction.

Electrochemical reduction of CO2 (CO2 RR) to value-added chemicals is an effective way to harvest renewable energy and utilize carbon dioxide. However, the electrocatalysts for CO2 RR suffer from insufficient activity and selectivity due to the limitation of CO2 activation. In this work, a Ni-doped Bi nanosheet (Ni@Bi-NS) electrocatalyst is synthesized for the electrochemical reduction of CO2 to HCOOH. Physicochemical characterization methods are extensively used to investigate the composition and structure of the materials. Electrochemical results reveal that for the production of HCOOH, the obtained Ni@Bi-NS exhibits an equivalent current density of 51.12 mA cm-2 at -1.10 V, which is much higher than the pure Bi-NS (18.00 mA cm-2 at -1.10 V). A high Faradaic efficiency over 92.0 % for HCOOH is achieved in a wide potential range from -0.80 to -1.10 V, and particularly, the highest efficiency of 98.4 % is achieved at -0.90 V. Both experimental and theoretical results reveal that the superior activity and selectivity are attributed to the doping effect of Ni on the Bi nanosheet. The density functional theory calculation reveals that upon doping, the charge is transferred from Ni to the adjacent Bi atoms, which shifts the p-orbital electronic density states towards the Fermi level. The resultant strong orbital hybridization between Bi and the π* orbitals of CO2 facilitates the formation of *OCHO intermediates and favors its activation. This work provides an effective strategy to develop active and selective electrocatalysts for CO2 RR by modulating the electronic density state.

Improved stability of ß-CsPbI3 inorganic perovskite using π-conjugated bifunctional surface capped organic cations for high performance photovoltaics.

Multiple-ring naphthalenediammonium is employed for the first time to overcome the intrinsic instability of ß-CsPbI3 perovskite via anchoring the ammonium groups occupying A-site vacancies. It improves charge transport and moisture stability giving out a champion power conversion efficiency of 16.69% for an excellent inorganic perovskite solar cell.

Efficient Nitrogen-Doped Carbon for Zinc-Bromine Flow Battery.

The zinc-bromine flow battery (ZBFB) is one of the most promising technologies for large-scale energy storage. Here, nitrogen-doped carbon is synthesized and investigated as the positive electrode material in ZBFBs. The synthesis includes the carbonization of the glucose precursor and nitrogen doping by etching in ammonia gas. Physicochemical characterizations reveal that the resultant carbon exhibits high electronic conductivity, large specific surface area, and abundant heteroatom-containing functional groups, which benefit the formation and exposure of the active sites toward the Br2 /Br- redox couple. As a result, the assembled ZBFB achieves a voltage efficiency of 83.0% and an energy efficiency of 82.5% at a current density of 80 mA cm-2 , which are among the top values in literature. Finally, the ZBFB does not yield any detectable degradation in performance after a 200-cycle charging/discharging test, revealing its high stability. In summary, this work provides a highly efficient electrode material for the zinc-bromine flow battery.