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Developing low-cost non-precious metal catalysts (NPMC) to replace Pt-based catalysts and rationally designing their integrated electrode to efficiently electrocatalyze oxygen reduction reaction (ORR) are greatly significant for facilitating the commercialization of fuel cells. Here, we report a novel self-supporting three-dimensional (3D) ordered integrated ORR electrode by a simple chemical vapor deposition (CVD) approach to in-situgrow Co,N co-doped carbon nanotubes (N-CNTs@Co) onto carbon paper modified by oxygen-containing functional groups (OCP). Benefiting from the moderate density of CNTs and abundant pyridinic N and graphitic N configurations as ORR active sites, the best-performing sample (N-CNTs-20@Co/OCP) exhibits outstanding ORR performance in both basic (0.1 mol L–1KOH) and acidic (0.1 mol L–1HClO4) media, which is comparable to the one fabricated through the conventional method by spraying commercial Pt/C (20 wt%) onto OCP substrate (0.2 mg Pt cm–2). This work can provide a feasible solution for the in-situconstruction of efficient NPMC-based ORR integrated electrode.

Deciphering the atomic-level properties and mechanism of electrocatalysts for water splitting is vital for the development of highly active non-noble-metal catalysts. Herein, we conduct a detailed study of layered crystalline CoMoO4using density functional theory (DFT) calculations. The layered arrangement of CoMoO4along the [110] lattice direction is observed, and the two thermodynamically stable and most exposed (110)A and (001)A crystal facets are selected among all low-index facets by surface energy calculations and Wulff construction to study the electrocatalytic activity for alkaline water splitting and corresponding mechanism. CoMoO4with an exposed (110)A facet (i.e., CMO (110)A) exhibited a high hydrogen evolution reaction (HER) activity, with a ΔGH*of 0.22 eV, which is similar to that of Pt because the adsorbed H is allowed to interact with two oxygen atoms (O3 and Oadj). The (110)A facet also possesses better H2O adsorption and dissociation abilities than the (001)A facet, benefiting the HER performance in alkaline solutions. Moreover, the overpotential of the (110)A facet for the electrocatalytic oxygen evolution reaction (OER) is only 0.74 V according to the Gibbs free-energy calculation, this overpotential is lower than that of the (001)A facet (0.84 V) owing to the stronger binding and more stable adsorption states between Co and O for the intermediate *O. By allowing us to identify highly active facets and sites, this approach guided the selective synthesis of CoMoO4and its isostructural substances, such as Mn(Ni, Fe)MoO4nanocatalysts, for alkaline water splitting.

To fully exploit the superiority of tubular structures, in this study, we systematically explore the optimal preparation conditions for Ni/Co3O4, including cation species and content, additive species and content, and anion species. Our results reveal that the formation of an initial cobalt nickel acetate hydroxide prism is the key factor and directly affects the final microtubular structure. Moreover, P is subsequently doped into the Ni/Co3O4lattice to increase the M3+/M2+molar ratio (M = Co and Ni), promote reaction kinetics, and optimize electronic structure. Consequently, the oxygen evolution reaction performance of P-doped tubular Ni/Co3O4is significantly higher than that of undoped Ni/Co3O4and the state-of-the-art RuO2electrocatalyst.

Hydrogen peroxide (H2O2) is a very useful chemical reagent, but the current industrial methods for its production suffer from serious energy consumption problems. Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction (ORR) through a two-electron (2e−) pathway is a very promising route to produce H2O2. In this work, we obtained partially oxidized multi-walled carbon nanotubes (MWCNTs) with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40°C for 1 h (O-CNTs-40-1). The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups, while the inner layers are maintained intact. The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity. The results of rotating ring disk electrode measurements reveal that, among all oxidized MWCNTs, O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity (from ∼ 30% to ∼ 50%) and electron transfer number (from ∼ 3.4 to ∼ 3.0) compared to those of the raw MWCNTs. The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs. Finally, direct tests of the H2O2production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.