Nanostructured Carbon-Nitrogen-Sulfur-Nickel Networks Derived From Polyaniline as Bifunctional Catalysts for Water Splitting

Self‐Supported Electrocatalysts Derived from Nickel‐Cobalt Modified Polyaniline Polymer for H2‐Evolution and O2‐Evolution Reactions

“…The mixture of the polymerization reaction underwent a solvent removal in a rotary evaporator to efficiently trap metal cations in the solid that will dry out afterwards at 80 °C. We previously found that this rotovap step is important because a simple filtration over Buchner results in the loss of Ni(II) and low yield of the synthesis [4b] . The second step was the thermal treatment to allow the assembling of Ni and Co elements into Ni−Co−X (X=O, S) particles that are self‐supported on a matrix made of C, N, S, Ni and Co. We hypothesized that the use of air as the environment for the thermal treatment instead of an inert gas such as nitrogen or argon will allow reaching an optimal compromise between the formation of a certain number of bipyramid nickel cobaltite particles onto a carbon‐nitrogen‐sulfur‐oxygen‐nickel‐cobalt network and the removal of excess carbon, chloride, and sulfur species.…”

“…The emerged scenario to tackle the above limitations is the one‐pot chemical polymerization in the presence of metallic cations followed by a proper thermal treatment to yield electrocatalysts with high activity [2c,4b,e] . We recently reported that the use of the ammonium persulfate (APS, (NH 4 ) 2 S 2 O 8 ) as the oxidizing agent and the nickel nitrate resulted in the fabrication of Ni 3 S 2 species after thermal treatment at 700–1000 °C; and demonstrated an outstanding efficiency towards HER and oxygen evolution reaction (OER) in alkaline media [4b] . Furthermore, nickel cobaltite (NiCo 2 O 4 ) was studied for a long time as a promising electrode for O 2 electrocatalysis [6] .…”

Iridium and Ruthenium Modified Polyaniline Polymer Leads to Nanostructured Electrocatalysts with High Performance Regarding Water Splitting

“…The different materials were synthesized by modifying our initial method [ 2 , 3 ]. Typically, 25 mL solution made of 0.5 M HCl and 0.4 M ANI was first prepared and put into a reactor at 5 °C.…”

“…Chung et al [ 1 ] have shown that an electrode’s electrical resistance (thus its conductivity) strongly affects the metrics of electrochemical activity and this becomes a concern for high mass loadings (increased thicknesses), before concluding that the electrical conductivity should be considered as one of the essential criteria when designing active materials for real electrochemical energy storage/conversion applications. The interest towards conducting polymer (nano)structures is growing yearly in (bio)electrochemistry as either precursors of freestanding electrocatalysts [ 2 , 3 ] or a supports [ 4 , 5 , 6 ] for active sites based on enzyme/abiotic catalysts. For both purposes, recent studies show that the combination of polyaniline (a conducting polymer) and metallic species (Ni, Co, Mo) produces nanostructured materials with high performance regarding the electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting [ 2 , 3 , 7 , 8 ].…”

“…Basically, those metal nanoparticles are initially prepared before the used of carbon black to lower the metal content, which does not enable the maximization of the electrocatalytic performance and minimization of the loss of active sites during the long-term operation. Hence, chemical polymerization in the presence of metallic cations combined with a proper thermal treatment seems to be an elegant approach to develop high-performance electrocatalysts for the half-cell reactions of water splitting (HER and OER), and previous results with polyaniline (PANI) testify to this [ 3 , 19 , 20 ]. However, given that HER and OER require either metallic or oxidized surfaces, the remaining major challenge is to find a unified method of synthesis that would allow the obtention of either metallic or oxidic nanostructured materials by adjusting the chemical content of the synthesis.…”