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Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion. In this regard, meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular-scale are vitally necessary. Herein, a coordination environment inheriting strategy is presented for designing low-coordination Ni2+ octahedra (L-Ni-8) atomic interface at a high concentration (4.6 at.%). Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode. To improve the efficiency of using the self-modification reaction environment at L-Ni-8, all of the structural features, including high atom economy, mass transfer, and electron transfer, are integrated together from atomic-scale to macro-scale. At high current density of 500 mA/cm2, the samples synthesized at gram-scale can deliver low hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of 262 and 348 mV, respectively. [ABSTRACT FROM AUTHOR]

Cuprous oxide catalysts have attracted much attention because they exhibited high selectivity of C2+ products in CO2 electroreduction, but the effect of the structure of catalysts on the reaction needs to be studied further. Herein, we studied the effect of the coordination number (CN) of Cu–Cu and Cu–O in Cu2O on the catalytic performance of CO2 electrocatalytic reduction to C2H4. It was demonstrated that Cu–Cu CN and Cu–O CN, which could be tuned by changing the crystal surface and size of Cu2O, influenced the current density and faradaic efficiency (FE) of C2H4 significantly. At suitable CNs, the FE of C2H4 could reach 50.6% with a current density of 24.5 mA cm−2. [ABSTRACT FROM AUTHOR]

Electroreduction of CO2 to liquid fuels such as ethanol and n‐propanol, powered by renewable electricity, offers a promising strategy for controlling the global carbon balance and addressing the need for the storage of intermittent renewable energy. In this work, we discovered that the composite composed of nitrogen‐doped graphene quantum dots (NGQ) on CuO‐derived Cu nanorods (NGQ/Cu‐nr) was an outstanding electrocatalyst for the reduction of CO2 to ethanol and n‐propanol. The Faradaic efficiency (FE) of C2+ alcohols could reach 52.4 % with a total current density of 282.1 mA cm−2. This is the highest FE for C2+ alcohols with a commercial current density to date. Control experiments and DFT studies show that the NGQ/Cu‐nr could provide dual catalytic active sites and could stabilize the CH2CHO intermediate to enhance the FE of alcohols significantly through further carbon protonation. The NGQ and Cu‐nr had excellent synergistic effects for accelerating the reduction of CO2 to alcohols. [ABSTRACT FROM AUTHOR]

For electrocatalysts for the hydrogen evolution reaction (HER), encapsulating transition metal phosphides (TMPs) into nitrogen‐doped carbon materials has been known as an effective strategy to elevate the activity and stability. Yet still, it remains unclear how the TMPs work synergistically with the N‐doped support, and which N configuration (pyridinic N, pyrrolic N, or graphitic N) contributes predominantly to the synergy. Here we present a HER electrocatalyst (denoted as MoP@NCHSs) comprising MoP nanoparticles encapsulated in N‐doped carbon hollow spheres, which displays excellent activity and stability for HER in alkaline media. Results of experimental investigations and theoretical calculations indicate that the synergy between MoP and the pyridinic N can most effectively promote the HER in alkaline media. [ABSTRACT FROM AUTHOR]

Selective reduction of ketone/aldehydes to alcohols is of great importance in green chemistry and chemical engineering. Highly efficient catalysts are still demanded to work under mild conditions, especially at room temperature. Here we present a synergistic function of single-atom palladium (Pd1) and nanoparticles (PdNPs) on TiO2 for highly efficient ketone/aldehydes hydrogenation to alcohols at room temperature. Compared to simple but inferior Pd1/TiO2 and PdNPs/TiO2 catalysts, more than twice activity enhancement is achieved with the Pd1+NPs/TiO2 catalyst that integrates both Pd1 and Pd NPs on mesoporous TiO2 supports, obtained by a simple but large-scaled spray pyrolysis route. The synergistic function of Pd1 and PdNPs is assigned so that the partial Pd1 dispersion contributes enough sites for the activation of C=O group while PdNPs site boosts the dissociation of H2 molecules to H atoms. This work not only contributes a superior catalyst for ketone/aldehydes hydrogenation, but also deepens the knowledge on their hydrogenation mechanism and guides people to engineer the catalytic behaviors as needed. Highly efficient catalysts are demanded to realize selective hydrogenation of ketone/aldehydes to alcohols under mild conditions. Here, the authors report a TiO2 supported Pd single-atom/nanoparticles synergistic catalyst with outstanding hydrogenation performance at room temperature. [ABSTRACT FROM AUTHOR]

Selective oxidation of toluene to benzoic acid (BAC) with benign oxidant O2 is of great importance, but remains a great challenge, especially using non-noble metallic catalysts. In this work, the Co@N/Co-CNT catalyst, which was composed of atomically dispersed CoN4 species embedded in N-doped CNTs and encapsulated Co nanoparticles, was synthesized. The loading CoN4 could reach 6.4 wt%. It was found that the catalyst exhibited outstanding performance for selective aerobic oxidation of toluene to BAC without additives under solvent-free conditions. The selectivity of BAC could be as high as 91.6% at a toluene conversion of 33.5%, which is much higher than the value reported to date, including those over noble metal-based catalysts. The control experiments indicated that the main active species were CoN4 sites and the outstanding catalytic performance of Co@N/Co-CNTs can be attributed mainly to the unique properties of the CoN4 species and its high loading in the catalyst. Furthermore, the Co@N/Co-CNTs also had an excellent catalytic performance in the selective aerobic oxidation of xylenes to toluic acid derivatives. [ABSTRACT FROM AUTHOR]

Insights into the real catalytic active site(s) of promising oxygen evolution reaction (OER) catalysts is significant for the further development of high-performance catalysts. Spinel cobalt oxide (Co3O4), with both tetrahedral (Co2+) and octahedral (Co3+) sites, has been widely studied as an efficient non-precious OER catalyst. However, controversial results still exist regarding its OER performance in determining the active sites from two different tetrahedral and octahedral sites. Here, we have designed size-controllable Co3O4 hexagonal platelets with (111) exposed surfaces only containing tetrahedral Co2+ sites as model catalysts, and systematically investigated the catalytic properties of the tetrahedral sites on the surface of the (111) plane and the octahedral sites on the surface of the (110)-B plane for the OER using density functional theory (DFT) and various characterization methods. The theoretical and experimental results further reveal that the high catalytic activity is based on the existence of octahedral sites in Co3O4, meaning that the octahedral sites are responsible for the OER reaction and have been identified as the dominant active sites of spinel Co3O4. [ABSTRACT FROM AUTHOR]

High-efficiency water electrolysis is the key to sustainable energy. Here we report a highly active and durable RuIrOx (x ≥ 0) nano-netcage catalyst formed during electrochemical testing by in-situ etching to remove amphoteric ZnO from RuIrZnOx hollow nanobox. The dispersing-etching-holing strategy endowed the porous nano-netcage with a high exposure of active sites as well as a three-dimensional accessibility for substrate molecules, thereby drastically boosting the electrochemical surface area (ECSA). The nano-netcage catalyst achieved not only ultralow overpotentials at 10 mA cm−2 for hydrogen evolution reaction (HER; 12 mV, pH = 0; 13 mV, pH = 14), but also high-performance overall water electrolysis over a broad pH range (0 ~ 14), with a potential of mere 1.45 V (pH = 0) or 1.47 V (pH = 14) at 10 mA cm−2. With this universal applicability of our electrocatalyst, a variety of readily available electrolytes (even including waste water and sea water) could potentially be directly used for hydrogen production. Water electrolysis is considered a key reaction for future sustainable fuel generation. Here, authors report a three-dimensional RuIrOx nano-netcage catalyst that shows high activities and efficiencies for pH-universal overall water splitting. [ABSTRACT FROM AUTHOR]