Optimization of hydrogen evolution reaction catalytic activity of Ti©üCO©ü via surface engineering with an isolated fluorine effect: An ab-initio density functional theory study Theoretical Approach toward Optimum Anion-Doping on MXene Catalysts for Hydrogen Evolution Reaction: an Ab Initio Thermodynamics Study Boosting oxygen evolution reaction of transition metal layered double hydroxide by metalloid incorporation Manipulatable Interface Electric Field and Charge Transfer in a 2D/2D Heterojunction Photocatalyst via Oxygen Intercalation