Engineering of cation and anion vacancies in Co3O4 thin nanosheets by laser irradiation for more advancement of oxygen evolution reaction

Plasma‐Assisted Synthesis of Co3O4‐Based Electrocatalysts on Ni Foam Substrates for the Oxygen Evolution Reaction

“…[ 21,35,48 ] This phenomenon suggests a concomitant slight surface reduction of Co 3 O 4 , in agreement with previous studies. [ 17,21,48,52,57,58 ]…”

“…Regardless of the synthesis conditions, the binding energy (BE) and spin‐orbit‐separation (SOS) of the Co2p peak [Figure 2b; BE(Co2p 3/2 ) = 780.2 eV; SOS = 15.2 eV], along with the low intensity of shake‐up satellites, confirmed the formation of Co 3 O 4 as the predominant cobalt oxide. [ 17,21,35,47,53,56,57 ] This conclusion was further supported by calculation of the cobalt Auger parameter (see also Figure 2c; α = 1552.6 eV). [ 47,56 ] As far as the Fe2p peak is concerned [Figure 2d; BE(Fe2p 3/2 ) = 711.2 eV; SOS = 13.4 eV], its spectral features were in good agreement with previous literature data for Fe 2 O 3.…”

“…[ 6,17,21,57,58 ] The higher surface defectivity of the last three specimens, arising from an effective plasma bombardment during the sputtering step (see above), might also be responsible for the appearance of the weak shake‐up features on the high BE side of Co2p 3/2 and Co2p 1/2 bands for samples Co(CVD)‐Fe(S) and Co(S)‐Fe(S) (see Figure 2b). [ 21,35,48 ] This phenomenon suggests a concomitant slight surface reduction of Co 3 O 4 , in agreement with previous studies. [ 17,21,48,52,57,58 ]…”

“…[ 7,12,16,17 ] Nevertheless, since bulk Co 3 O 4 presents a low surface area and—similarly to many transition metal oxides—suffers from a modest electronic conductivity, the full exploitation of its electrochemical performances inevitably requires a tailored design and engineering of the anode structure. [ 5,16,18–23 ] To this aim, important degrees of freedom are offered by a proper choice of the substrate, the modulation of the catalyst properties, and, eventually, the introduction of suitable co‐catalysts, whose synergistic interactions with Co 3 O 4 may afford a favorable improvement of the resulting electrochemical behavior. As concerns the substrate, the use of porous and highly conductive scaffolds enables an efficient catalyst dispersion and adhesion on the substrate, providing thus favorable pathways for both mass and charge transport.…”

“…[ 13,24,27–29 ] In addition, the nanoscale control of Co 3 O 4 characteristics, including exposed crystallographic facets and oxygen vacancy content, are effective means to enhance electrical conductivity and tailor material reactivity, [ 5,17,30–34 ] improving the ultimate catalytic performances. [ 1,2,5,6,11,12,16,21,22,26,35 ] The latter can be further boosted by functionalization of Co 3 O 4 with a suitable co‐catalyst, often a second nanostructured metal oxide. Successful examples include Co 3 O 4 coupling with Fe 2 O 3 , NiO, CuO, or ZnO nanoparticles (NPs), [ 26,36–39 ] whose introduction can result in an increased amount of active sites, and promote a synergistic catalytic/electronic interplay between the system components.…”