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.image

Selective oxygen reduction reaction: mechanism understanding, catalyst design and practical application

“…Therefore, researchers can rely on in situ or other advanced characterization techniques to capture key active intermediates during the catalytic activation process and gain a more comprehensive understanding of the reaction mechanism. 97–99 However, no single technique is universally applicable due to inherent limitations based on their principles. Therefore, using a combination of multiple characterization techniques and multiple instruments is the future direction of characterization technology development.…”

Interfacial Electron Modulation to Boost Driving Force: Partial Sulfurization over Co-MOF@Fe2O3 p–n Heterojunctions for Water Splitting

“…However, when the applied potential is increased from 1.5 to 1.6 V, two new peaks ranged around 400−600 cm −1 can be assigned to the M−O vibration of the surface M−OOH intermediates, which have been normally recognized as the most efficient intermediates of the OER process for kinetics. 37 Typically, a clear change has been detected at approximately 1.6 V for Co-MOF@Fe 2 O 3 , 1.5 V for Co-MOF@Fe 2 O 3 −S, and 1.6 V for CoS 2 @Fe 2 O 3 . Notably, Co-MOF@Fe 2 O 3 −S presents the lowest applied potential.…”

“…When at a lower voltage than 1.5 V, all of the Raman peaks are hardly changed during the anodic OWS process, illustrating that the entire electrode is stable. However, when the applied potential is increased from 1.5 to 1.6 V, two new peaks ranged around 400–600 cm –1 can be assigned to the M–O vibration of the surface M–OOH intermediates, which have been normally recognized as the most efficient intermediates of the OER process for kinetics . Typically, a clear change has been detected at approximately 1.6 V for Co-MOF@Fe 2 O 3 , 1.5 V for Co-MOF@Fe 2 O 3 –S, and 1.6 V for CoS 2 @Fe 2 O 3 .…”

Insight into the Anticorrosion Behaviors of Phase-Transformed Cobalt Hydroxides for Long-Term Electrocatalytic Water Oxidation in Saline Electrolytes

“…Cobalt hydroxide has been widely used as an OER catalyst in alkaline environments. − However, it is a precatalyst that experiences phase transformations to the active Co 3+ - or Co 4+ -containing species, such as amorphous Co oxy-hydroxides. , In this regard, extensive studies have been conducted to identify the OER active sites of Co­(OH) 2 both in α- and β-phases. − Nevertheless, the understanding in the structural evolution of Co­(OH) 2 during OER and CER processes is deficient, which is critical for the application and optimization of Co­(OH) 2 for superior catalytic performance in alkaline saline water. Herein, we focus on an electrodeposited α-Co­(OH) 2 on a nickel foam (NF) substrate and investigate the anticorrosion behaviors in alkaline saline electrolytes (1.0 M KOH and 0.5 M NaCl).…”