Atomically ultrathin rhodium nanosheets obtained by the cyanogel reduction method demonstrate an excellent electrocatalytic activity for the nitrogen reduction reaction.

CC bond cleavage, resulting in the low fuel utilization and less than theoretical 12 elections transfer. [12,13] Thus, improving the ability of electrocatalysts for splitting CC bond is critical for the development and application of DEFCs. [14][15][16] At present, Pt is the most effective monometallic electrocatalyst for the EOR. However, expensive price and weak ability of splitting CC bond seriously hamper its commercial applications. [10,17] Recently, alloying Pt with other metal is generally considered as an efficient strategy for decreasing the cost of electrocatalyst and simultaneously improving electrocatalytic activity for the EOR. [18][19][20][21] For example, the addition of Ru and Rh elements can obviously promote the CC bond cleavage, which is beneficial to the C 1 reaction pathway of the EOR. The introduction of highly oxophilic metals (such as Ni and Cu) can decrease the CO poisoning of electrocatalyst due to the bifunctional mechanism. [17,22,23] Considering that CC bond cleavage and CO poisoning, trimetallic Pt-based electrocatalysts have been designed to simultaneously improve their CC bond cleavage capability and antipoisoning capability. For example, PtPdRh [24] and PtRhNi [22] alloys nanoparticles displayed the excellent electrocatalytic activity for the EOR.Apart from chemical composition, the morphology of nanostructures also strongly affects their electrocatalytic performance. [25][26][27][28][29][30] For example, hollow nanostructures generally show enhanced activity and stability due to their unique advantages, including large surface area, abundant active sites, high atomic utilization, rich holes, fast mass transfer, stable 3D structure, and slow Ostwald ripening. [31][32][33][34][35] Given the effect of chemical composition and morphology on the EOR performance, herein, we designed and synthesized the porous trimetallic PtRhCu cubic nanoboxes (CNBs) by the galvanic reaction between K 2 PtCl 4 , RhCl 3 , and Cu 2 O nanocubes template. The shell thickness and chemical composition of PtRhCu CNBs could be easily regulated by controlling the amount and proportion of noble metal precursors. Due to geometric effect and alloy effect, the composition optimized PtRhCu CNBs exhibited a significantly enhanced C 1 pathway selectivity for the EOR, resulting in super electrocatalytic activity and stability. Additionally, the template method could also be used to synthesize other trimetallic cubic nanoboxes (such as PtIrCu and PtAuCu CNBs), showing its universality.Direct ethanol fuel cells (DEFCs) have great activity as a green energy conversion device. However, the weak activity of most anode electrocatalysts for the CC bond cleavage is an obstacle to the DEFCs development. Herein, a simple galvanic replacement reaction strategy to synthesize hollow and porous PtRhCu trimetallic nanoboxes (CNBs) with a tunable Pt/Rh atomic ratio is developed. For the ethanol oxidation reaction (EOR), PtRhCu CNBs show morphology and composition-dependent electrocatalytic activity. The composition optimized Pt...

Ammonia plays a signi cant role in agriculture and the next-generation carbon-free energy supply.Electrocatalytic nitrate reduction to NH 3 is attractive for nitrate removal and NH 3 production under ambient conditions. However, the energy e ciency is limited by the high reaction overpotential. Here, we propose a three-step relay mechanism composed of a spontaneous redox reaction, electrochemical reduction, and electrocatalytic reduction to overcome this issue. Ru x Co y alloys are designed and adopted as model catalysts. Ru 15 Co 85 exhibits an onset potential of +0.4 V versus a reversible hydrogen electrode and an energy e ciency of 41.54 ± 1.72 %, which are both the best records. The high performance results in a low production cost of $0.49 ± 0.02 /kg ammonia ($0.58~1.02/kg ammonia sold in the USA).Electrochemical in situ spectroscopy and theoretical simulations indicate that the three-step relay mechanism leads to excellent catalytic performance on Ru 15 Co 85 and can be extended to Ru x Fe y and Ru x Ni y alloys.