A double-exchange interaction (DEI) was demonstrated to boost the oxygen evolution reaction (OER) in spinel oxides. DEI was ignited by synergistic actions of constructing nanoheterojunctions and creating oxygen vacancy (V O ) in spinel NiCo 2 O 4 . DEI between octahedrally coordinated Ni and Co resulted in the generation of superior OER active centers Co (3−δ)+ and Ni 3+ . The multiple synergistic effects empower the electrocatalyst with exceptional OER activity, with an overpotential of 270 ± 3 mV at 10 mA/cm 2 and a Tafel slope of 39 mV/dec, both of which are among the best values for NiCo 2 O 4 -based nanostructures, and even better than those for IrO 2 and RuO 2 . Communication pubs.acs.org/JACS

A class of Pd−Ni−P electrocatalysts are prepared for the ethanol electrooxidation reaction (EOR). Xray diffraction and transmission electron microscope reveal that the synthesized Pd−Ni−P catalyst possesses a more amorphous structure with smaller particle sizes when compared with a Pd−Ni sample without P and a control Pd black (Pd-blk) sample. The Pd−Ni−P catalyst contains double the number of electrocatalytically active sites (12.03%) compared with the Pd−Ni (6.04%) and Pd-blk (5.12%) samples. For the EOR, the Pd−Ni−P catalyst has the lowest onset potential (−0.88 V vs SCE), the most negative peak potential (−0.27 V vs SCE), and the highest EOR activity in 0.1 M KOH solution. Moreover, a 110 mV decrease in overpotential is observed for the EOR on the Pd−Ni−P catalyst compared with the Pd-blk catalyst. A Tafel slope of 60 mV/dec at low polarization potentials (<−0.76 V vs SCE) was obtained for EOR at a Pd−Ni−P-coated electrode with a reaction rate constant of 2.8 × 10 −4 cm•S −1 •M −1 at −0.3 V vs SCE in KOH media. Finally, we find that the electrooxidation of ethanol on the Pd−Ni−P catalyst undergoes a 4-electron process to acetate.

Multimetallic nanoclusters (MMNCs) offer unique and tailorable surface chemistries that hold great potential for numerous catalytic applications. The efficient exploration of this vast chemical space necessitates an accelerated discovery pipeline that supersedes traditional “trial-and-error” experimentation while guaranteeing uniform microstructures despite compositional complexity. Herein, we report the high-throughput synthesis of an extensive series of ultrafine and homogeneous alloy MMNCs, achieved by 1) a flexible compositional design by formulation in the precursor solution phase and 2) the ultrafast synthesis of alloy MMNCs using thermal shock heating (i.e., ∼1,650 K, ∼500 ms). This approach is remarkably facile and easily accessible compared to conventional vapor-phase deposition, and the particle size and structural uniformity enable comparative studies across compositionally different MMNCs. Rapid electrochemical screening is demonstrated by using a scanning droplet cell, enabling us to discover two promising electrocatalysts, which we subsequently validated using a rotating disk setup. This demonstrated high-throughput material discovery pipeline presents a paradigm for facile and accelerated exploration of MMNCs for a broad range of applications.

Focusing on methanol tolerance, a series of heat-treated metalloporphyrins were investigated by steady-state voltammetry with a rotating disk electrode. The heat-treated CoTPP/FeTPP (tetraphenylporphyrin) shows the optimum catalytic activity for oxygen reduction with an onset catalytic potential [0.9 V vs. reversible hydrogen electrode (RHE)] close to that of platinum black catalyst (1.0 V vs. RHE). However, the catalytic activity for oxygen reduction on platinum black catalyst is severely affected by the presence of 1.0 M methanol, resulting in a negative shift of the catalytic potential and a significant decrease in catalytic current. The catalytic activity for oxygen reduction on the heat-treated metalloporphyrin is not appreciably affected by the presence of the same amount of methanol in an acidic electrolytic solution. The catalytic activity of the heat-treated binary metalloporphyrin catalyst is better than that of only a heat-treated single metalloporphyrin. The best heat-treatment (HT) temperature for HT-CoTPP/FeTPP is 600ЊC. The catalytic kinetic process is analyzed using various polarization curves for oxygen reduction at different rotation rates. The slopes obtained from the Koutecky ´-Levich plots have verified that the heat-treated metalloporphyrins can catalyze a four-electron reduction of oxygen to water over a wide potential range.