Catalytic hydrolysis of sodium borohydride for hydrogen generation using g-C3N4/Co–W–B/Ni foam composite catalyst

In this study, electroless plating method was adopted for the first time to prepare double-loaded g-C3N4/Co–W–B/NF (NF = Ni foam) catalysts. Different g-C3N4/Co–W–B/NF catalysts were obtained by changing the molar ratio of initial Co2+ and WO42− (nCo2+:nWO42-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{n}}_{{\mathrm{Co}}^{2+}}{:\mathrm{n}}_{{\mathrm{WO}}_{4}^{2-}}$$\end{document}) in the catalyst plating solution, and their catalytic effects were tested for catalyzing hydrolysis of NaBH4 solution to release hydrogen (H2). Among them, when nCo2+:nWO42-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{n}}_{{\mathrm{Co}}^{2+}}{:\mathrm{n}}_{{\mathrm{WO}}_{4}^{2-}}$$\end{document} value was 5:5, g-C3N4/Co–W–B/NF exhibited the best catalytic activity on the hydrolysis of NaBH4 solution. Its released H2 rate was 7328 mL·min−1 g−1 under visible light irradiation, which outperformed 6191 mL·min−1 g−1 of g-C3N4/Co-B/NF catalyst. The activation energy reduced from 45.6 kJ mol−1 of g-C3N4/Co-B/NF to 31.5 kJ mol−1 of g-C3N4/Co–W–B/NF under visible light irradiation. The result showed that adding an appropriate amount of W played a significant role in promoting the catalytic performance in NaBH4 hydrolysis. Moreover, under visible light irradiation, a possible mechanism was proposed on g-C3N4/Co–W–B/NF catalyst toward the H2 generation from NaBH4 hydrolysis.