Transition metal-doped ultrathin RuO₂ networked nanowires for efficient overall water splitting across a broad pH range

Abstract

Although water splitting has been successfully achieved in recent years, the design of highly efficient bifunctional catalysts applicable across a broad pH range, especially in harsh acidic conditions, remains full of challenges.

Stable overall water splitting in an asymmetric acid/alkaline electrolyzer comprising a bipolar membrane sandwiched by bifunctional cobalt‐nickel phosphide nanowire electrodes

“…In the presence of the BPM, water electrolysis can be accomplished with E onset = 1.439 V and E 10 = 1.567 V (red trace in Figure 3A), which is not only better than the above‐mentioned AEM‐WE but also higher than PEM water electrolysis carried out in 0.5M H 2 SO 4 using commercially available RuO 2 as OER catalysts and Pt/C as HER catalysts (denoted as RuO 2 ‖PEM‖Pt/C), separated by a commercial Nafion 115 membrane (FuelCellStore; E onset = 1.432 V and E 10 = 1.608 V; magenta trace in Figure 3A). 20 Moreover, the electrochemical performance of the noble‐metal‐free asymmetric BPM‐based water electrolyzer is favorably comparable to that of many other electrolyzers using noble metal catalysts for HER and OER that were reported recently (1.44‐1.58 V@10 mA/cm 2 ), 20‐28 showing the advantage of the BPM configuration for overall water electrolysis. It is worth noting that even compared with the BPM‐based asymmetric water electrolysis using RuO 2 as the OER catalysts and Pt/C as the HER catalysts (denoted as RuO 2 ‖BPM‖Pt/C; E onset = 1.407 V and E 10 = 1.59 V; blue trace in Figure 3A), the performance of Co‐Ni‐P/NF‖BPM‖Co‐Ni‐P/NF is still better, due likely to the higher loading of Co‐Ni‐P NWs and the favorable monolithic configuration of Co‐Ni‐P/NF including the vertically aligned NW array architecture, better adhesion of Co‐Ni‐P NW catalysts to the NF current collector and the absence of polymeric binder, which facilitate the electron and mass transfer during the HER and OER.…”

Recent Development of Oxygen Evolution Electrocatalysts in Acidic Environment

“…[72][73][74] The studies on morphology are classified into three categories in this section. First, 1D structures, such as nanoneedles [72] and nanowires [75][76][77][78] showing high conductivity have been prepared for improving OER activity. For example, ultrathin IrO 2 nanoneedles were introduced as electrocatalyst for OER in acidic electrolyte (Figure 5a,b).…”

Na/Al Codoped Layered Cathode with Defects as Bifunctional Electrocatalyst for High‐Performance Li‐Ion Battery and Oxygen Evolution Reaction

“…On the contrary, codoping has significantly suppressed the phase transition from layered to nanodomain spinels, [ 26 ] which is regarded as a major shortcoming to initiate voltage fade in layered cathodes. [ 27 ]…”

“…Recently, Na substituion in perovskite SrRuO 3 significantly improved the durability toward OER, [ 25 ] wehreas Pt‐introduced Ru 0.9 Pt 0.1 O 2 /C electrocatlyst exhibited improved stability. [ 26 ] Likewise, codoped RuO 2 nanowires demonstrated improved alkaline stability [ 27 ] and RuO 2 /N–C showed high OER activity. While in cathode active materials, Fe substitution in LiNiO 2 significantly enhanced its OER activity, [ 28 ] electrochemically delithiated LiCo 1/3 Ni 1/3 Fe 1/3 O 2 demonstrated a notable performance, [ 29 ] and similarly a lithiated spinel LT‐LiCoO 2 also improved the water oxidation.…”