Converging Hydrogen-Bonded Water Transport Channel with External Magnetic Field in a Janus Molecular Cobalt Phosphate for Enhanced Oxygen Evolution Reaction (OER) Activity
T. Prapakaran, Ananya Chowdhury, Sunita Sharma, Itisha Dwivedi, Gopalan Rajaraman, Chandramouli Subramaniam, Ramaswamy Murugavel
Abstract
Increasing the water content and the hydrophobic accessibility through hydrogen-bonded dimeric cavities of Janus-faced mononuclear Co(II) phosphates, pristine complex [Co(Cl-tpy)(dtbppH) 2 (H 2 O)]·(H 2 O)(2MeOH) ( 1-xtal ), and sonicated [Co(Cl-tpy)(dtbppH) 2 (H 2 O)]·(H 2 O) n ( 1-soni ) produces systematic increments in the anodic water-splitting reaction (OER), which is further enhanced by an external magnetic field (50–300 mT), with water-rich 1-soni exhibiting the best electrocatalytic activity and energy efficiency. Such enhanced catalytic activity is traced to spin-state switching of a key intermediate formed during the catalytic cycle, offering a lower kinetic barrier from denisty functional theory calculations. Since the energy gap between these spin states is small, this suggests preferential switching of state with a lower kinetic barrier in the presence of a magnetic field, rationalizing the observed behavior.