Dual-laser pulse-patterned α-Co(OH)2/rGO heterointerface for accelerated water oxidation and surface phase-transition via in-situ Raman spectroscopy

Abstract

The dynamic surface reconstruction of electrodes is a legible sign to understand the deep phase-transition mechanistic and electrocatalytic origin during the oxygen evolution reaction (OER). Herein, we report a dual-laser pulse-patterned heterointerface of α-Co(OH)₂ and reduced graphene oxide (rGO) nanosheets via pulsed laser irradiation in liquid (PLIL) to accelerate OER kinetics. α-Co(OH)₂ was formed from the OH⁻ ions generated during the PLIL of GO at neutral pH. Co²⁺ modulation in tetrahedral coordination sites benefits as an electrophilic surface for water oxidation. Few d-vacancies in Co²⁺ increase its affinity toward oxygen, lowering the energy barrier and generating many CoOOH and CoO₂ active sites. rGO with an ordered π-conjugated system aids the surface adsorption of OOH*, O*, and OH* during OER. α-Co(OH)₂ surface phase-transition and OER mechanistic steps occurred via phase-reconstruction to CoOOH and CoO₂ reactive intermediates, uncovered using in situ electrochemical–Raman spectroscopy. Our findings in the dual-laser pulse strategy and the surface reconstruction correlation in active OER catalysts pave the path for paramount in multiple energy technologies.