Colloidal core/shell quantum dots (QDs) with environment-friendly feature and controllable optoelectronic properties are promising building blocks in emerging solar technologies. In this work, we rationally design and tailor the eco-friendly CuInSe (CISe)/ZnSe core/shell QDs by Mn doping and stoichiometric optimization (i.e., molar ratios of Cu/In). It is demonstrated that Mn doping in In-rich CISe/ZnSe core/shell QDs can effectively engineer the charge kinetics inside the QDs, enabling efficient photogenerated electrons transfer into the shell for retarded charge recombination. As a result, a solar-driven photoelectrochemical (PEC) device fabricated using the optimized Mn-doped In-rich CISe/ZnSe core/shell QDs (Cu/In ratio of 1/2) exhibits improved charge extraction and injection, showing a ~ 3.5-fold higher photocurrent density than that of the pristine CISe/ZnSe core/shell QDs under 1 sun AM 1.5G illumination. The findings indicate that transition metal doping in “green” nonstoichiometric core/shell QDs may offer a new strategy for achieving high-efficiency solar energy conversion applications.

To develop highly efficient electrochemical catalysts for N₂ fixation is important to sustainable ambient NH₃ production through the N₂ reduction reaction (NRR). Herein, we demonstrate the development of vanadium phosphide nanoparticle on V foil as a high- efficiency and stable catalyst for ambient NH₃ production with excellent selectivity. The high Faradaic efficiency of 22% with a large NH₃ yield of 8.35 × 10^-11 mol·s^-1·cm^-2 was obtained at 0 V vs. the reversible hydrogen electrode in acid solution, superior to all previously studied V-based NRR catalysts. Density functional theory calculations are also utilized to have an insight into the catalytic mechanism.