Hydrogen (H 2 ), a regenerable and promising energy carrier, acts as an essential role in the construction of a sustainable energy system. Formic acid (HCOOH, FA), a natural biological metabolic products and also accessible through carbon dioxide (CO 2 ) reduction, has a great potential to serve as a prospective H 2 supplier for the fuel cell. Herein, ultrafine and electron-rich IrPdAu alloy nanoparticles with a size of 1.4 nm are highly dispersed on amine-modified mesoporous SiO 2 (NH 2 -SBA-15) and used as a highly active and selective catalyst for fast H 2 production from FA. The as-synthesized IrPdAu/NH 2 -SBA-15 possesses superior catalytic activity and 100% H 2 selectivity with initial turnover frequency values of 6316 h −1 with the additive of sodium formate (SF) and 4737 h −1 even without SF at 298 K, comparable to the most effective heterogeneous catalysts ever published. The excellent performance of IrPdAu/NH 2 -SBA-15 was not only ascribed to the combination of the electronic synergistic effect of trimetallic alloys and the strong metal−support interaction effect but also attributed to the amine (−NH 2 ) alkaline groups grafted on SBA-15, which is beneficial to boost the split of the O−H bond of FA.

HIGHLIGHTS • Utilizing 3D printing allows the fine construction of electrodes with tailorable thickness and precise tuning of mass loading of active materials. • 3D-printed NiCoP/MXene//AC asymmetrical supercapacitor full cells harvest a record-high areal/volumetric energy density of 0.89 mWh cm −2 /2.2 mWh cm −3 .

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For nickel-based catalysts, in-situ formed nickel oxyhydroxide has been generally believed as the origin for anodic biomass electro-oxidations. However, rationally understanding the catalytic mechanism still remains challenging. In this work, we demonstrate that NiMn hydroxide as the anodic catalyst can enable methanol-to-formate electro-oxidation reaction (MOR) with a low cell-potential of 1.33/1.41 V at 10/100 mA cm−2, a Faradaic efficiency of nearly 100% and good durability in alkaline media, remarkably outperforming NiFe hydroxide. Based on a combined experimental and computational study, we propose a cyclic pathway that consists of reversible redox transitions of NiII-(OH)2/NiIII-OOH and a concomitant MOR. More importantly, it is proved that the NiIII-OOH provides combined active sites including NiIII and nearby electrophilic oxygen species, which work in a cooperative manner to promote either spontaneous or non-spontaneous MOR process. Such a bifunctional mechanism can well account for not only the highly selective formate formation but also the transient presence of NiIII-OOH. The different catalytic activities of NiMn and NiFe hydroxides can be attributed to their different oxidation behaviors. Thus, our work provides a clear and rational understanding of the overall MOR mechanism on nickel-based hydroxides, which is beneficial for advanced catalyst design.

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Potassium‐ion batteries (KIBs) have come into the spotlight in large‐scale energy storage systems because of cost‐effective and abundant potassium resources. However, the poor rate performance and problematic cycle life of existing electrode materials are the main bottlenecks to future potential applications. Here, the first example of preparing 3D hierarchical nanoboxes multidimensionally assembled from interlayer‐expanded nano‐2D MoS2@dot‐like Co9S8 embedded into a nitrogen and sulfur codoped porous carbon matrix (Co9S8/NSC@MoS2@NSC) for greatly boosting the electrochemical properties of KIBs in terms of reversible capacity, rate capability, and cycling lifespan, is reported. Benefiting from the synergistic effects, Co9S8/NSC@MoS2@NSC manifest a very high reversible capacity of 403 mAh g−1 at 100 mA g−1 after 100 cycles, an unprecedented rate capability of 141 mAh g−1 at 3000 mA g−1 over 800 cycles, and a negligible capacity decay of 0.02% cycle−1, boosting promising applications in high‐performance KIBs. Density functional theory calculations demonstrate that Co9S8/NSC@MoS2@NSC nanoboxes have large adsorption energy and low diffusion barriers during K‐ion storage reactions, implying fast K‐ion diffusion capability. This work may enlighten the design and construction of advanced electrode materials combined with strong chemical bonding and integrated functional advantages for future large‐scale stationary energy storage.

Very recently, a variety of undoped carbons have been employed as electrocatalysts for the oxygen reduction reaction (ORR), based on the defect mechanism. Nevertheless, the defective carbon catalyst with sufficiently high ORR activity is still very rare. In this work, we report a series of defective carbon catalysts prepared through a facile and scalable "N-doping-removal" process using seaweed biomass sodium alginate (SA) as precursor. Our systematic studies reveal that the defect content, porosity characteristic and conductivity of defective carbons can be finely tuned by manipulating the pyrolysis temperature and viscosity of precursor polymer SA, which significantly affect the ORR performance. In 0.1 M KOH, compared to the commercial Pt/C catalyst, the optimized catalyst D-PC-1(900), with abundant ORR-active defects, a large surface area of 1377 m 2 g-1 , a Smicro/meso ratio of 0.6 and good conductivity, exhibited very comparable ORR activity and selectivity. In 0.5 M H2SO4, considerable ORR activity was also observed for D-PC-1(900), which is among the highest reported for defective carbons and comparable to many of N-doped carbons. Density functional theory calculations indicate that the carbon defect can create the active sites for ORR in acidic media. More importantly, in both alkaline and acidic media, D-PC-1(900) shows much better stability and methanol tolerance than those of the Pt/C catalyst. All these results demonstrate that the seaweed biomass derived defective carbon is an excellent candidate for non-precious-metal ORR catalyst in various fuel cells.